Improve
To have your hand increase in strength from your initial holding, either by the community or board cards in hold em type games, or by drawing cards from the deck, in draw poker.

Should you have, in texas holdem, an ace and a king in your hole cards, with a flop of ace, king, seven, you are holding two pairs, aces and kings. Should the turn card be an ace then your hand has improved from two pairs to a full house.