1. [n]  a thin varnish made by dissolving lac in ethanol; used to finish wood
2. [n]  lac purified by heating and filtering; usually in thin orange or yellow flakes but sometimes bleached white
3. [v]  cover with shellac, as of wooden objects; "She wanted to shellac the desk to protect it from water spots"

SHELLAC is a 7 letter word that starts with S.