Accessorily is an uncommon word that means "as an accessory" or "by way of addition." Though replacing accessorily with a synonym may not be necessary in most cases, expanding one's vocabulary is never a bad idea. Some synonyms for accessorily include incidentally, secondarily, supplementally, ancillarily, and additionally. Using these words instead of accessorily can add variety and sophistication to one's writing or speech. For example, "I studied philosophy in college, but music was just an ancillary interest of mine" or "The project's success was secondary to the team's cohesion".