IPA: /ˈboʊstfəl.nəs/
KK: /ˈboʊstfəl/
The quality of talking about oneself or one's achievements in a way that shows too much pride.
His boastfulness made it hard for others to appreciate his true talents.
Boastfulness is formed from "boast" (from Old French *boaster*, meaning to brag or boast) and "-fulness" (meaning the state of being full of). The word describes the state of being full of boast or pride in one's achievements.
Think of someone who is 'full of bragging' — 'boast' means to brag, and '-fulness' indicates a state of being. This helps you remember that boastfulness refers to the state of being boastful.