Pavilion
Middle English (denoting a large decorated tent): from Old French pavillon, from Latin papilio(n- ) ‘butterfly or tent’.
wiktionary
From Middle English pavilloun, from Anglo-Norman pavilloun, from Latin pāpiliōnem, form of pāpiliō(“butterfly, moth”) (due to resemblance of tent to a butterfly’s wings), of unknown origin. [1] Doublet of papillon.
Cognate to French pavillon(“pavilion”) and papillon(“butterfly”), and similar terms in other Romance languages.
etymonline
pavilion (n.)
early 13c., paviloun, "large, stately tent raised on posts and used as a movable habitation," 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 was so called on its resemblance to wings. Meaning "open building in a park, etc., used for shelter or entertainment" is attested from 1680s. Sense of "small or moderate-sized building, isolated but dependent on a larger or principal building" (as in a hospital) is by 1858.
