Noun

1. An older person who accompanies other younger people to ensure the propriety of their behaviour, often an older woman accompanying a young woman.
2. A protein that assists the non-covalent folding/unfolding and the assembly/disassembly of other macromolecular structures, but does not occur in these structures when the latter are performing their normal biological functions.

Verb

1. to act as a chaperone
   • 2006, The New Yorker, 17 April 2006, page 27.

     'Purcell had volunteered to chaperone a delegation of female students'