add–on

something that is not necessary in itself but adds to the convenience or performance of the main piece of equipment a blow-dryer that comes with a couple of add-ons for people who are serious about styling their hair Synonyms accoutrement (or accouterment), adapter (also adaptor), add-on, adjunct, appendage, appliance, attachment, optionRelated Words accompaniment, additive, complement, supplement; auxiliary, subsidiary; amenity, doodad, embroidery, extra, filler, frill, incidental, luxury, nonessential, nonnecessity; appurtenances, bells and whistles, equipment, furnishings, habiliment(s), paraphernalia, trappings; adornment, decoration, embellishment, enhancement, garnish, ornament, trim, trimmingNear Antonyms essential, necessity, requirement, requisite