Origin and history of rathskeller

early 13c., "store room," from Anglo-French celer, Old French celier "cellar, underground passage" (12c., Modern French cellier), from Latin cellarium "pantry, storeroom," literally "group of cells;" which is either directly from cella "small room, store-room" (from PIE root *kel- (1) "to cover, conceal, save"), or from noun use of neuter of adjective cellarius "pertaining to a storeroom," from cella. The sense "room under a house or other building, mostly underground and used for storage" gradually emerged in late Middle and early Modern English. Related: Cellarer. Cellar-door attested by 1640s.

German federal council, 1879, from German Bundestag, from genitive of Bund "league, confederacy, association" (related to English band (n.2) and bind (v.)) + tag, literally "day;" as a verb, tagen, "to sit in conference" (see day; also compare adjourn). Hence also Bundesrat "federal council of the German empire" (1872), from rat, rath "council" (see rathskeller).