The English word "gala" today means "festival, celebration." But it originally meant "festive dress." Klein suggests an Arabic origin, as mentioned here:
Klein suggests the French word is from Italian gala (as in phrase vestito di gala "robe of state"), perhaps from Arabic khil'a "fine garment given as a presentation."
The word khi'la, in turn, derives from the Arabic khala'a - "to divest [oneself of one's robe]." (It also might mean to put on the robe, and so would be an example of a contronym, a word that also means its opposite, as we discussed here.) Could this verb - "to remove, to take off, to depose" - have a cognate in Hebrew?
Very possibly. The connection may be found through a cognate: halal - "permitted" meat according to Islamic law. Just as in Hebrew, the word for permitted, mutar מותר, literally means "untied, loose," so too does the Arabic halal. (This is the opposite of haram - "prohibited, sacred," as we showed when discussing the Hebrew cognate cherem.)
Halal is allowed for use, and so could be defined as "profane" (i.e. not religiously forbidden.) In this way it is cognate with the Hebrew root חלל chalal, and the noun chol חול - both meaning "profane" (and today "secular.") Klein provides the following etymology for that root:
Aram. חֲלַל, Syr. אַחֵל (= he profaned), Arab. ḥalla (= he united, undid), ḥall (= the profane, allowed for use).
I think that there is a likely typo in Klein here, and halla should be defined as "he untied", not "he united."
Stahl provides a similar development, saying both the Hebrew and Arabic roots mean "released" - which applies to robes of honor, meat from ritual prohibition, and all things from their sacred status.