The term 'drain opener' refers to a substance used to clear clogged drains. The three crossword solutions for this term are LYE (3 letters), DEE (3 letters), and LYESOAP (7 letters). LYE is an alkaline substance, usually sodium hydroxide, that is used to dissolve grease and other organic matter in drains. DEE is a type of LYE made from animal fat and LYE, and is often used as a drain opener. LYESOAP is a combination of LYE and soap, which is also used to unclog drains.