too big for one's breeches is an adjective meaning "(used colloquially) overly conceited or arrogant". It carries one recorded sense.
(used colloquially) overly conceited or arrogant
“a snotty little scion of a degenerate family”
“they're snobs--stuck-up and uppity and persnickety”
Definitions, synonyms and semantic relations for too big for one's breeches come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.