epiglottis

Concise Oxford English Dictionary © 2008 Oxford University Press:
epiglottis /ˌɛpɪˈglɒtɪs/

▶noun a flap of cartilage behind the root of the tongue, which is depressed during swallowing to cover the opening of the windpipe.

– derivatives
epiglottal adjective,
epiglottic adjective.

– origin ME: from Gk epiglōttis, from epi ‘upon, near to’ + glōtta ‘tongue’.