IPA: /ˈæptnəs/
KK: /ˈæptnəs/
A quality of being suitable or appropriate for a particular purpose or situation. It can also refer to a person's natural ability to learn or understand things quickly.
Her aptness for mathematics was evident from a young age, as she easily grasped complex concepts.
Aptness → It is formed from "apt" (from Latin "aptus", meaning suitable or fit) and the suffix "-ness" (meaning the state or quality of). The word "aptness" refers to the quality of being suitable or fitting for a particular purpose.
Think of 'apt' meaning suitable, and remember that 'aptness' describes the quality of being suitable.