Epigram originally ment simply "an inscription
started using it to mean a short poem
, usually a solemn
one. Then the Romans
changed it's meaning again, this time using it to mean a short witty poem, with a barb
at the end.
We have a pretty witty king,
Whose word no man relies on,
Who never said a foolish thing,
Nor ever did a wise one.
John Wilmot, Earl of Rochester
The word now also means any clever thought in verse or in prose.