AP'ERTURE, noun 1. The act of opening; more generally, an opening; a gap, cleft or chasm; a passage perforated; a hole through any solid substance. 2. An opening of meaning; explanation. [Not used.] 3. In geometry, the space between two right lines, forming an angle.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI