Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
vespertilionidae is a noun meaning "the majority of common bats of temperate regions of the world". It carries one recorded sense.
the majority of common bats of temperate regions of the world
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for vespertilionidae come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.