Lewis & Short

ĭnānĭo, īvi or ĭi, ītum, 4, v. a. [inanis], to make empty, to empty out, evacuate (poet. and in post-Aug. prose): hoc ubi inanitur spatium, etc., Lucr. 6, 1005; cf.: locus inanitus magis ac vacuatus, ib. 1025: herbacea arefacta per se inanit alvum, Plin. 20, 3, 8, § 14: vesicas (polium), id. 21, 20, 84, § 146: corpora (luna, opp. implet), id. 2, 98, 99, § 122.
Part. as subst.: ĭnānītum, i, n., vacancy, emptiness (opp. plenum), Tert. Res. Carn. 4.