aptness

noun4

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
2. •
   Disposition of the mind; propensity.
3. •
   Proneness; tendency.
4. •
   Speed or readiness in learning; docility.

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