vestibular (adj.)

1620s, "a porch," later "antechamber, lobby" (1730), from French vestible, from Latin vestibulum "forecourt, entrance," of unknown origin. In reference to the ear part from 1728.

word-formation element meaning "pertaining to, of the nature of," from Latin -arem, -aris "of the kind of, belonging to," a secondary form (by dissimilation) of -alis, used after syllables with an -l- (such as insularis for *insulalis, stellaris for *stellalis).