A yawn (synonyms chasma, oscitation from the Latin verb oscitare, to open the mouth wide[1]) is a reflex of deep inhalation and exhalation associated with being tired, with a need to sleep, or fromlack of stimulation. :- :^o
1. highly excitable; unnaturally or acutely uneasy or apprehensive: to become nervous under stress.
2. of or pertaining to the nerves: nervous tension.
3. affecting the nerves: nervous diseases.
4. suffering from, characterized by, or originating in disordered nerves.
5. characterized by or attended with acute uneasiness or apprehension:
6. having or containing nerves.
7. sinewy or strong.
8. Archaic. vigorous or spirited.