·noun Proneness; tendency; as, the aptness of iron to rust.
II. Aptness ·noun Disposition of the mind; propensity; as, the aptness of men to follow example.
III. Aptness ·noun Fitness; suitableness; appropriateness; as, the aptness of things to their end.
IV. Aptness ·noun Quickness of apprehension; readiness in learning; docility; as, an aptness to learn is more observable in some children than in others.