Words that refer collectively to one’s clothes have an origin in the sense of equipment or preparation; here are a dozen words available as alternatives to clothes.
Apparel, ultimately derived from the Latin verb apparare, meaning “prepare,” started out in English as a verb but then came to be associated with clothing (as well as a ship’s rigging); apparatus is related. The origin of attire is the French word atirier, meaning “equip” or “prepare”; it, too, began as a verb.
Clothes comes from the Old English plural of cloth. (When this sense became rare, cloth acquired a new plural: cloths.) Costume, from the Latin word consuetudinem, meaning “custom” or “habit” (costume and custom are cognate), was later associated with one’s style of dress. It is now mostly associated with clothing worn by performers or partygoers.
Dress, which originally meant “prepare,” derives ultimately from the Latin term directus, meaning “direct” or “straight,” and later became a noun as well as a verb. The French term garnement, from the noun garner, meaning “adorn” or “provide” (also the source of garnish) was adopted into English as garment.
Habiliments, from the Old French term abiller, meaning “equip” or “prepare,” originally referred to weaponry but came to pertain to characteristic attire, such as an outfit worn to identify a person’s occupation or tacitly prescribed clothing that is appropriate for a specific occasion, such as a formal-dress event. (Related words are able and ability, billet, habit, and habilitate.)
Outfit originally meant to prepare and supply a sea expedition, then later became a noun referring to equipment and items required for such an undertaking by sea or by land and, by extension, to clothing. (It now also informally refers to a group of people.)
The archaic word raiment derives from an Old French word areement, the noun form of the term areer, the origin of the English verb (and noun) array. Vestments comes ultimately from the Latin verb vestire, meaning “clothe,” by way of Old French; it’s related to vest. (Vestibule is unrelated, though the financial sense of vest, and the root word in invest and divest, are cognate, deriving from a sense of vestire that pertains to surrounding oneself with something figuratively as if putting on clothes.)
Wardrobe, from the Old French word garderobe (and the dialectical variant warderobe), originally referred to a dressing room, then to one’s collection of clothing and later to a piece of furniture for storing clothing; the senses derive from the French warder, meaning “guard” or “keep,” and robe, which was directly borrowed into English to refer to a garment. The French form of the word has been used in English but is rare. (The connection between g and w in French words used in English is also seen, for example, in guarantee/warranty and Guillaume/William.)
Wear, from an Old English term meaning “clothe” or “cover up” (and related to the ward in wardrobe), is generally used in combination to refer to a particular type of clothing, as in the terms sportswear and underwear.
Slang terms for clothing include duds, garb, get-up, rags, rig, threads, and togs.