anteroom (antechamber) or small foyer leading into a larger space
A floor plan with a modern vestibule shown in red Vestibule in Germany.
A vestibule (also anteroom, antechamber, outer room, windbreak room, air-lock entry, or foyer) is a small room leading into a larger space such as a lobby, entrance hall, or passage, for the purpose of waiting, withholding the larger space from view, reducing heat loss (air trap, windbreak), providing storage space for outdoor clothing (mudroom), etc. The term applies to structures in both modern and classical architecture since ancient times.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).