The term monumental sculpture is often used in art history and criticism, but not always consistently. It combines two concepts, one of function, and one of size, and may include an element of a third more subjective concept. It is often used for all sculptures that are large. Human figures that are perhaps half life-size or above would usually be considered monumental in this sense by art historians, although in contemporary art a rather larger overall scale is implied. Monumental sculpture is therefore distinguished from small portable figurines, small metal or ivory reliefs, diptychs and the like.
It is also used of sculpture that is architectural in function, especially if used to create or form part of a monument of some sort, and therefore capitals and reliefs attached to buildings will be included, even if small in size. Typical functions of monuments are as grave markers, tomb monuments or memorials, and expressions of the power of a ruler or community, to which churches and so religious statues are added by convention, although in some contexts monumental sculpture may specifically mean just funerary sculpture for church monuments.
The third concept that may be involved when the term is used is not specific to sculpture, as the other two essentially are. The entry for "Monumental" in A Dictionary of Art and Artists by Peter and Linda Murray describes it as:
The most overworked word in current art history and criticism. It is intended to convey the idea that a particular work of art, or part of such a work, is grand, noble, elevated in idea, simple in conception and execution, without any excess of virtuousity, and having something of the enduring, stable, and timeless nature of great architecture. ... It is not a synonym for 'large'.
However, this does not constitute an accurate or adequate description of the use of the term for sculpture, though many uses of the term that essentially mean either large or "used in a memorial" may involve this concept also, in ways that are hard to separate. For example, when Meyer Schapiro, after a chapter analysing the carved capitals at Moissac, says: "in the tympanum of the south portal [(right)] the sculpture of Moissac becomes truly monumental. It is placed above the level of the eye, and is so large as to dominate the entire entrance. It is a gigantic semi-circular relief ...", size is certainly the dominant part of what he means by the word, and Schapiro's further comments suggest that a lack of "excess of virtuousity" does not form part of what he intends to convey. Nonetheless, parts of the Murray's concept ("grand, noble, elevated in idea") are included in his meaning, although "simple in conception and execution" hardly seems to apply.