aptness

Noun

1. Suitability; 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...
2. Disposition of the mind; propensity.
   • the aptness of men to follow example
3. Speed or readiness in learning; docility.
   • An aptness to learn is more observable in some children than in others.
4. Proneness; tendency.
   • the aptness of iron to rust