"She comes across as a bumptious [ˈbʌmpʃəs], irritating ten-year-old who believes that her main vice, her steam-roller self-confidence, is a virtue." — Lloyd Evans, The Spectator (London), 17 Aug. 2024

bumptious
adj [ˈbʌmpʃəs]

Bumptious describes people who are rudely and often noisily confident or over-assertive. It can also be applied to actions or behaviors that show this same attitude.

...ours notes that it comes from the noun bump and the suffix -tious, echoing other disapproving modifiers including captious ("fault-finding") and fractious ("troublemaking").

English