wit 1 
(wĭt)
(wĭt)n.
Idioms: 1.
a. The natural ability to perceive and understand; intelligence.
b. often wits Practical intelligence; shrewdness or resourcefulness: living by one's wits.
c. wits Sound mental faculties; sanity: scared out of my wits.
d. Archaic A person of exceptional intelligence.
2.
a. The ability to express oneself intelligently in a playful or humorous manner, often in overturning audience expectations: a writer with a scintillating wit.
b. A person noted for this ability, especially in conversation: “My mother, the family wit and teaser, knew better than to joke about the disaster” (Donald Hall).
c. Intelligent playfulness or humor in expression, as in speech, writing, or art: novels known for their wit and inventiveness.
at (one's) wits' end
At the limit of one's mental resources; utterly at a loss.
have (or keep)(one's) wits about (one)
To remain alert or calm, especially in a crisis.
[Middle English, from Old English; see weid- in the Appendix of Indo-European roots.]