| n. | 1. | Fitness; suitableness; appropriateness; |
| 2. | Disposition of the mind; propensity; | |
| 3. | Quickness of apprehension; readiness in learning; docility; | |
| 4. | Proneness; tendency; |
| Noun | 1. | aptness - a disposition to behave in a certain way; "the aptness of iron to rust"; "the propensity of disease to spread" Synonyms: propensity |
| 2. | aptness - appropriateness; "the phrase had considerable aptness" Synonyms: appositeness Antonyms: inappositeness, inaptness - in appropriateness; "greater inaptness of expression would be hard to imagine" |