Learn That Word

Synonyms for Too Big For One's Breeches (same or very similar meaning)

WordNet sense 1 ((used colloquially) overly conceited or arrogant):
persnickety, snooty, snot-nosed, snotty, stuck-up, uppish, bigheaded

WordNet sense 2 (feeling self-respect or pleasure in something by which you measure your self-worth; or being a reason for pride):

From the ODE community, based on WordNetadd/edit