朊病毒 ruǎnbìngdú prion Origin Definitions Defs Strokes Stroke Words Sentences Sents 朊 ruǎn protein (bound form) an older term for protein; used primarily in scientific compounds like 朊病毒 ruǎnbìngdú病毒 bìngdú noun virus a type of tiny microorganism that causes infection and can only reproduce inside the living cells of a host