Despair is a noun meaning the complete loss or absence of hope.
As a verb, to despair means to lose or be without hope.
Common expressions with despair:
1. "In despair" - feeling hopeless
2. "Despair of" - to lose hope about something
3. "Cry of despair" - an expression of complete hopelessness
4. "Sink into despair" - to become very hopeless