gismu – core verbs

The brivla which constitute the lexical core of the language are called gismu. They are invariably five-letter words, which distinguishes it from the other types of brivla, and are in a form of either CVCCV or CCVCV (C stands for a consonant and V for a vowel). Being two syllables means that the general rule of brivla to be stressed penultimately will always cause the first syllable of a gismu to be stressed.

They have been chosen or added as root words because they

• represent concepts that are very familiar and basic,
• represent concepts the usage of which is equally frequent among different languages,
• would be helpful in constructing more complex words, or
• represent fundamental grammatical concepts of Lojban.^[18]

The main source languages from which they were drawn are Arabic, Chinese, English, Hindi, Russian, and Spanish. Here is further explanation of the nature of gismu by Cowan:

The gismu do not represent any sort of systematic partitioning of semantic space. Some gismu may be superfluous, or appear for historical reasons: the gismu list was being collected for almost 35 years and was only weeded out once. Instead, the intention is that the gismu blanket semantic space: they make it possible to talk about the entire range of human concerns. [...] For a given concept, words in the six languages that represent that concept were written in Lojban phonetics. Then a gismu was selected to maximize the recognizability of the Lojban word for speakers of the six languages by weighting the inclusion of the sounds drawn from each language by the number of speakers of that language.

The Complete Lojban Language: 4.4

According to Robin Turner,^[23] the creation was algorithmically done by computer.

Approximately 1350 gismu exist, which is a relatively small number when compared to that of English words ranging from 450,000 up to 1,000,000.^[24] Theoretically, by learning only these root words, as well as their fragmental forms and some major structure words (cmavo), one will be able to communicate effectively in Lojban.

lujvo – verbs made of affixes

The form of brivla made of affixes (rafsi) is called lujvo.

fu'ivla – borrowed verbs, loan words

fu'ivla usually refers to things that are culture-specific (including Lojban culture) or to kinds of plants or animals, concepts which cannot be easily expressed as mere modifying-modified combinations of Lojban's internal root verbs (gismu).

fu'ivla can be subdivided into four types according to the extent to which they are modified, namely Stage 1, 2, 3, and 4 fu'ivla.

lujvo with components made of fu'ivla

It is possible to absorb a fu'ivla into a lujvo, with principles varying among Lojbanists. Notable proponents are Pierre Abbat and Jorge Llambías. Here are some comparisons of their methods drawn from the Lojban mailing list (as of July 2007):

description

Basic descriptions in Lojban consist of two units, LE/LA descriptors and a selbri:

le zarci

Although le is quite close in meaning to English "the", it has particularly unique implications. In this example, le creates an argument which might occur in the x1 place of the belonging selbri zarci, namely a "market". le also specifies that the speaker 1) has one or more specific markets in mind (whether or not the listener knows which ones they are) and 2) is merely describing the things he/she has in mind as markets, without being committed to the truth of that description. Whereas English-speakers must differentiate between "the market" and "the markets", Lojban-speakers are not required to make such a choice (this rule does not mean that Lojban has no way of specifying the number of markets in such a case):

le zarci cu barda
The market is big. / The markets are big.

Since the construct le + selbri merely describes something or other which the speaker chooses to represent based on his/her observation, such an expression as follows is possible:

le nanmu cu ninmu
one-or-more-specific-things-which-I-describe as "men" are women

While le is specific, lo is not:

lo zarci cu barda
one-or-more-of-all-the-things-which-really are-markets is/are-big
A market is big. / Some markets are big.

lo refers generally to one or more markets, without being specific about which. Unlike le zarci, lo zarci must refer to something which actually is a market (that is, which can appear in the x1 place of a truthful bridi whose selbri is zarci). lo morsi cu jmive is false as there are no objects in the real world which are both dead and alive.

la dissociates the subsequent selbri from its normal meaning, usually making a name (this usage should not be confused with the other usage before regular Lojbanized names). Like le descriptions, la descriptions are implicitly restricted to those the speaker has in mind:

la cribe pu finti le lisri
the-one-named "bear" [past] creates the story.
Bear wrote the story.

All descriptions implicitly terminate with ku, which can almost always be omitted with no danger of ambiguity. The main exceptions are a) when relative clauses are involved and b) when a description immediately precedes the selbri (in which case using an explicit cu before the selbri makes the ku unnecessary). Other usages of ku include making a compound negator (naku) and terminating place-structure/tense/modal tags (puku, baiku).

tanru – compound verbs

This section needs expansion. You can help by adding to it. (August 2007)

A group of two or more selbri put one after another is called tanru and acts as a single selbri (while the selbri it is composed of are called tanru units (selbrisle)). They correspond to English compound verbs like drip fry or drip dry.

Tanru can be converted to sumti as usual selbri.

Tanru may be used so as to more specifically conceptualize the intended meaning. In lo skami pilno ("computer user(s)"), there is a tanru skami pilno where the modifying brivla skami narrows the sense of the modified brivla pilno to form a more specific concept (in which case the modifier may resemble English adverbs or adjectives). Without skami, lo pilno will just mean "user". Other examples:

Arguments of selbri representing tanru units may be filled as well, in which case they are attached using the particle be (starting from x2 place of the tanru unit):

Descriptors

There are five descriptors (gadri in Lojban): lo, le, la, li, and me'o; of which the first three inflect to show individual, mass, or set (though as far as the formal grammar is concerned, the inflected forms are separate words, not inflected forms).

The individual/mass distinction is similar to the distinction between mass nouns and count nouns, but things that are normally counted can be considered as a mass. The set articles consider the mathematical set of the referents.

The number and mathematical expression articles are used when talking about numbers and numerals or letters as themselves.

Note that gadri are sometimes called articles, which doesn't correspond to the usual notion of articles in linguistics.

Connectives

As befits a logical language, there is a large assortment of conjunctions.

There exist 16 possible different binary truth functions, the four fundamental ones of which are assigned four vowels in Lojban. These vowels are a component sound from which actual logical-connective cmavo are built up.

A	FIRST is true and/or SECOND is true (TTTF)
E	FIRST is true and SECOND is true (TFFF)
O	FIRST is true if and only if SECOND is true (TFFT)
U	FIRST is true whether or not SECOND is true (TTFF)

With the four vowels, the ability to negate either sentence (with na or nai), and the ability to exchange the sentences, as if their order had been reversed (with se), Lojban can create all of the 16 possible truth functions except TTTT and FFFF.

More information , ...

	Original form	Negating first	Negating second	Negating both
A	(A) .a (B)	(A) na.a (B)	(A) .anai (B)	(A) na.anai (B)
	${\displaystyle A\lor B}$	${\displaystyle \neg A\lor B}$ ${\displaystyle A\rightarrow B}$	${\displaystyle A\lor \neg B}$ ${\displaystyle A\leftarrow B}$	${\displaystyle \neg A\lor \neg B}$ ${\displaystyle A\uparrow B}$
	A or B	If A, then B	A if B	A NAND B A or B, not both
E	(A) .e (B)	(A) na.e (B)	(A) .enai (B)	(A) na.enai (B)
	${\displaystyle A\wedge B}$	${\displaystyle \neg A\wedge B}$ ${\displaystyle A\nleftarrow B}$	${\displaystyle A\wedge \neg B}$ ${\displaystyle A\nrightarrow B}$	${\displaystyle \neg A\wedge \neg B}$ ${\displaystyle A\downarrow B}$
	A and B	Not A but B	A but not B	Neither A nor B
O	(A) .o (B)	(A) na.o (B)	(A) .onai (B)	(A) na.onai (B)
	${\displaystyle A\leftrightarrow B}$	${\displaystyle \neg A\leftrightarrow B}$ ${\displaystyle A\oplus B}$	${\displaystyle A\leftrightarrow \neg B}$ ${\displaystyle A\oplus B}$	${\displaystyle \neg A\leftrightarrow \neg B}$ ${\displaystyle A\leftrightarrow B}$
	A if and only if B	A or B, not both	A or B, not both	A if and only if B
U	(A) .u (B)	(A) na.u (B)
	${\displaystyle A}$	${\displaystyle \neg A}$
	A, regardless of B	Not A, regardless of B
	(A) se.u (B)	(A) se.unai (B)
	${\displaystyle B}$	${\displaystyle \neg B}$
Regardless of A, B	Regardless of A, not B

Close

.onai is preferred over na.o. Note that in se.unai, the negation occurs before "swapping" the positions of A and B. While se can be used for the other connectives, it is unnecessary since or, and, and if and only if have the same relationship if their inputs are swapped (i.e. they are commutative).

FFFT	(A) na.enai (B)	${\displaystyle A\downarrow B}$	Neither A nor B
FFTF	(A) na.e (B)	${\displaystyle A\nleftarrow B}$	Not A but B
FFTT	(A) na.u (B)	${\displaystyle \neg A}$	Not A (regardless of B)
FTFF	(A) .enai (B)	${\displaystyle A\nrightarrow B}$	A but not B
FTFT	(A) se.unai (B)	${\displaystyle \neg B}$	(Regardless of A) Not B
FTTF	(A) .onai (B)	${\displaystyle A\oplus B}$	A or B, not both
FTTT	(A) na.anai (B)	${\displaystyle A\uparrow B}$	A NAND B
TFFF	(A) .e (B)	${\displaystyle A\wedge B}$	A and B
TFFT	(A) .o (B)	${\displaystyle A\leftrightarrow B}$	A if and only if B
TFTF	(A) se.u (B)	${\displaystyle B}$	(Regardless of A) B
TFTT	(A) na.a (B)	${\displaystyle A\rightarrow B}$	If A then B
TTFF	(A) .u (B)	${\displaystyle A}$	A (regardless of B)
TTFT	(A) .anai (B)	${\displaystyle A\leftarrow B}$	A if B
TTTF	(A) .a (B)	${\displaystyle A\lor B}$	A or B

In order to remain unambiguous, each place in the grammar of the language where logical connection is permitted has its appropriate set of connectives. If the connective suitable for sumti were used to connect selbri, ambiguity would result. Connections between components other than sumti can be expressed as follows (note that their functions are in accordance with the assigned vowels):

Negatives and se can be used with these connectives with similar forms.

Connections can also be given using "forethought" forms

Negatives are created by adding nai to the connective before the negated construct.

Connections can be questioned:

Besides the logical connectives, there are several non-logical connectives. These do not change form depending on what they are connecting:

(A) joi (B)	the mass with components A and B
(A) ce (B)	the set with elements A and B
(A) ce'o (B)	the sequence with elements A and B in order
(A) sece'o (B)	the sequence with elements B and A in order
(A) jo'u (B)	A and B considered jointly
(A) fa'u (B)	A and B respectively
(A) sefa'u (B)	B and A respectively
(A) jo'e (B)	the union of sets A and B
(A) ku'a (B)	the intersection of sets A and B
(A) pi'u (B)	the cross product of sets A and B
(A) sepi'u (B)	the cross product of sets B and A

The ku is required by the LALR parser, but not by the PEG parser, which however is not official yet.

Attitudinals

Attitudinals are a set of cmavo which allow the speakers to express their emotional state or source of knowledge, or the present stage of discourse. In natural languages, attitudes are expressed using interjections, but also by the tone of voice when speaking, and (very imperfectly) by punctuation when writing; in Lojban, such information are extensively expressible in words. And the meanings are to be understood separately from the main predicate.

They may be "scaled" by suffixes:

Combination is possible, and highly productive as well as creative:

Evidentials, derived from those of American Indian languages and the constructed language Láadan, show how the speaker came to say the utterance, i.e. the source of the information or the idea:

Prepositions

There are two kinds of prepositions (sumtcita, which refers to adpositions in general) in Lojban: tense markers and proper prepositions. The syntactic difference is that a proper preposition can be converted with se, whereas a tense marker cannot. All proper prepositions (except the vague one do'e) are formed from a brivla and mark their object semantically as being in a place of that brivla. Thus the following are equivalent:

Prepositions (including tense markers) can also be placed in .i ... bo to make sentence conjunctions. With most prepositions this makes no sense, but ki'u, ja'e, mu'i and ni'i are often used this way to express various kinds of "because" and "therefore":

la .djan. cpacu le pamoi se jinga .iki'ubo ri jinga
John got the first prize because he won.

Tense words

Lojban has 63 unique tense words to express various aspects of both space and time as well as event: such a system is unusual among other languages, in that it deals with spatial and temporal aspects in the same term. Simply put, these tense words are used to show where and when the event is taking place, relative in space-time to when the sentence is spoken. They can be roughly subdivided as follows:

The "converters" require further explanation: mo'i marks that the movement is towards (or away from, etc.) a point rather than at a point, so that be'a, meaning "(occurring) in the north", becomes mo'ibe'a, "(heading) northward"; roi marks the number of times an event takes place, e.g. paroi (once), roroi (always), noroi (never), re'u indicated an ordinal, e.g. pare'u, first time; fe'e marks an interval in space rather than in time, so that, for example, fe'e co'a is the "beginning point" of something physically extending in a given direction; jai is used to mark tense words that have been moved in a sentence, comparable to se/te/ve/xe and fa/fe/fi/fo/fu for sumti; ki marks a "sticky tense", as explained below.

Marking tenses is always optional in Lojban:

Where the tense information is not specified, the context resolves the interpretation.

Tense words are usually put right before the selbri:

mi [cu] pu klama le zarci (cu is the implicit separator between the first sumti mi and the selbri klama.)

They may be placed elsewhere with the additional terminator ku:

The terminator is used so that the tense word do not directly run into the following sumti and modify it. Compare the next sentences:

Tenses can be "layered up":

mi pu klama le zdani .i le zdani pu pu se daspo
I [past] go-to the house. The house [past][past] be-destroyed.
I went to the house. The house had been destroyed.

Tenses can be "sticky" by being set with ki, continuing in effect over more than a single bridi, until it is unset:

mi pu ki fengu binxo .i le nixli cu klaku cfari .i mi ki xenru
I [past]-[set this tense] angry-kind-of become. The girl crying-kind-of start. I [set this tense] regret.
(Earlier) I got angry. The girl started crying. (Now) I regret.

The second ki resets the tense to the implicit default time from the speaker's point of view, which is "now" (this means that ki may be used as a tense word by itself).

Using ki, equivalents of the previous layering tenses can be produced:

mi puki klama le zdani .i le zdani pu se daspo

The second pu is to be counted from the tense set by the last ki, so in effect it is equivalent to pupu.

Similar to the tense words are a collection of words to show potentiality: ca'a, "actually is"; ka'e, "is innately capable of"; nu'o, "can but has not"; pu'i, "can and has". These words operate in the same way as tense words.

Grouping

Semantic unifications and combinations are performed by word groupings, each include a starting and a | often elidable) terminating cmavo. Here basic example sentences with them are ordered by their terminating cmavo: