A hole card higher than any rank of card on the board in a Texas Holdem or Omaha poker game. A higher card on the board to any hole cards is an overcard to your hole cards.
In flop games, a card higher than the highest card on the board. If you hold AJ and the flop is J92, you have top pair with an overcard. If the flop is T92, you just have two overcards.
A pocket card or cards higher than any card on the board. For instance a player holds A K on a board of 7 2 5. Conversely, community cards higher than a player's hole cards. For instance a player holds 5 6 and the flop is 10 Q A.