despair (v.)

"to lose hope, be without hope," mid-14c., despeiren, from Old French despeir-, stressed stem of desperer "be dismayed, lose hope, despair," from Latin desperare "to despair, to lose all hope," from de "without" (see de-) + sperare "to hope," from spes "hope" (from PIE root *spes- "prosperity;" see speed (n.)). Related: Despaired; despairing; despairingly.

despair (n.)

c. 1300, despeir, "hopelessness, total loss of hope," from Anglo-French despeir, Old French despoir, from desperer (see despair (v.)). The native word was wanhope.

Despair naturally destroys courage and stops all effort, but may produce a new kind of courage and fierce activity founded upon the sense that there is nothing worse to be feared. In this despair is akin to desperation, which is an active state and always tends to produce a furious struggle against adverse circumstances, even when the situation is utterly hopeless. [Century Dictionary, 1897]

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Definitions of despair from WordNet
despair (n.)
a state in which all hope is lost or absent;
in the depths of despair
they were rescued from despair at the last minute
Synonyms: desperation
despair (n.)
the feeling that everything is wrong and nothing will turn out well;
one harsh word would send her into the depths of despair
they moaned in despair and dismay
despair (v.)
abandon hope; give up hope; lose heart;
Don't despair--help is on the way!