the.com/skillfulness

means The quality of being skilled — proficiency gained through ability honed by training and repetition.

from Built from 'skillful' plus the noun suffix '-ness.' 'Skill' traces back to Old Norse 'skil,' meaning distinction, discernment, or reason — the ability to tell one thing from another and judge rightly. So the deep root isn't just dexterity, it's good judgment; the hands-on competence came later, as discernment turned into know-how.