Apt"ness, n. 1. Fitness;
suitableness; appropriateness; as, the aptness of things to their
end.
The aptness of his quotations.
J. R. Green.
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. Proneness; tendency; as, the aptness of
iron to rust.