pavilionyoudaoicibaDictYouDict
pavilion: [13] Pavilion got its name because some anonymous ancient Roman was reminded by a tent, with its two ‘wings’ spread out from a central crosspiece, of a ‘butterfly’. Latin for ‘butterfly’ was pāpiliō (a word of unknown origin), which hence came to be used for ‘tent’. English acquired it via Old French pavillon.
pavilion (n.)youdaoicibaDictYouDict
c. 1200, "large, stately tent," from Old French paveillon "large tent; butterfly" (12c.), from Latin papilionem (nominative papilio) "butterfly, moth," in Medieval Latin "tent" (see papillon); the type of tent so called on resemblance to wings. Meaning "open building in a park, etc., used for shelter or entertainment" is attested from 1680s.