say it: VEH-sti-byool
vestibule is a noun meaning "a large entrance or reception room or area". It carries 2 recorded senses.
a large entrance or reception room or area
any of various bodily cavities leading to another cavity (as of the ear or vagina)
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 vestibule come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.