From The Collaborative International Dictionary of English v.0.48:
Pithy \Pith"y\, a. [Compar. Pithier; superl. Pithiest.]
1. Consisting wholly, or in part, of pith; abounding in pith;
as, a pithy stem; a pithy fruit.
[1913 Webster]
2. Having nervous energy; forceful; cogent.
[1913 Webster]
This pithy speech prevailed, and all agreed.
--Dryden.
[1913 Webster]
In all these Goodman Fact was very short, but pithy.
--Addison.
[1913 Webster]
Pithy gall (Zool.), a large, rough, furrowed, oblong gall,
formed on blackberry canes by a small gallfly
(Diastrophus nebulosus).
[1913 Webster]