formal Antonyms

informal prothalamium undiscreet unpleasant unpolitic unwritten vernacular verse versicle versification villanelle virelay wilting unceremonious procedural kamikaze pidgin unconsiderate triolet quatrain relaxed respectless rhyme rondeau rondel roundelay slangy sonnet spoken supra sweetened tanka terminology theretofore thoughtless native language slanguage idiolect sporty subliterary sub-par subpar unceremoniously thick as thieves unceremonial undignified unvigilant as thick as thieves terrified of scared of