aptness

plural aptnesses

1. countableuncountableSuitability; the quality of being apt or suitable.

   A regular supply of coking slack is sent from Durham to the Scunthorpe area, in view of its special aptness for steelmaking processes, [...].

   1962 August, G. Freeman Allen, “Traffic control on the Great Northern Line”, in Modern Railways, page 128

2. countableuncountableDisposition of the mind; propensity.

   the aptness of men to follow example

3. countableuncountableSpeed or readiness in learning; docility.

   An aptness to learn is more observable in some children than in others.

4. countableuncountableProneness; tendency.

   the aptness of iron to rust