The word "shellack" refers to a coating or varnish that is applied to an object to give it a glossy and smooth finish. Some antonyms of "shellack" include words like dull, rough, unpolished, and unfinished. These words describe the opposite of a polished and smooth surface. Other antonyms for "shellack" include words like weathered, aged, and distressed, which describe a surface that is intentionally made to look old and worn out. Finally, words like matte, satin, and flat can also be considered antonyms of "shellack" as they describe a surface that lacks gloss and shine.