An overpair is a pair made from a player's own cards that is higher than anyt pair that could be made with the community cards.

Example (Texas Hold'em):

Player Board
The player has a pair of aces, which is higher than any card on the board and so higher than any pair that could be made with them. Therefore, it is an overpair.

Related Topics:

Underpair, Pair, Top Pair, Middle Pair, Bottom Pair