APT'NESS, noun 1. Fitness; suitableness; as, the aptness of things to their end. 2. Disposition of the mind; propensity; as, the aptness of men to follow example. 3. Quickness of apprehension; readiness in learning; docility; as, an aptness to learn is more observable in some children than in others. 4. Tendency, in things; as, the aptness of iron to rust.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI