Merriam-Webster Collegiate Dictionary - chaperone

 I. noun  or chaperon  Etymology: French chaperon, literally, hood, from Middle French, head covering, from chape  Date: 1720  1. a person (as a matron) who for propriety accompanies one or more young unmarried women in public or in mixed company  2. an older person who accompanies young people at a social gathering to ensure proper behavior; broadly one delegated to ensure proper behavior  3. any of a class of proteins that facilitate the proper folding of proteins by binding to and stabilizing unfolded or partially folded proteins — called also molecular ~  II. verb  or chaperon  (-oned; -oning)  Date: 1796  transitive verb  1. escort  2. to act as ~ to or for ~ a dance chaperoning teenagers  intransitive verb to act as a ~  • chaperonage noun