imperceptible
adjective
[ ɪmpəˈsɛptɪb(ə)l ]
• so slight, gradual, or subtle as not to be perceived.
• "his head moved in an almost imperceptible nod"
Similar:
unnoticeable,
undetectable,
indistinguishable,
indiscernible,
unapparent,
inappreciable,
invisible,
inaudible,
impalpable,
unobtrusive,
impossible to detect,
slight,
small,
subtle,
faint,
fine,
inconsequential,
negligible,
tiny,
minute,
minuscule,
microscopic,
nanoscopic,
infinitesimal,
indistinct,
unclear,
obscure,
vague,
indefinite,
shadowy,
hard to make out,
Origin:
late Middle English: from French, or from medieval Latin imperceptibilis, from in- ‘not’ + perceptibilis, from the verb percipere (see perceive).
