knack Definition

knack
noun

1. The ability to do something effectively and skilfully.

Thesaurus: aptitude, ability, skill, faculty, bent, capacity, gift, talent, flair, adroitness, dexterity, facility, forte.
2. A habit or tendency, especially an intuitive or unconscious one.

Thesaurus: tendency, inclination, bent, propensity.

Etymology: 14c: probably related to obsolete knack a sharp blow or sound.