O- Odds
- The chances of making a hand compared to not making it
- Off Suit
- Two cards, typically hole cards, that have different suits
- Omaha
- A version of poker similar to Hold `Em, but with four hole cards
- Omaha Hi/Lo
- A version of poker similar to Hold `Em, but with four hole cards and the pot split between the best high and low hands
- On Board
- The cards that make up the community cards
- One-Gap
- A Hold `Em starting hand with two cards two apart in rank, e.g. 8and 6 or T and Q
- Open Ended Straight Draw
- Four cards to a straight where a card ranking above or below the run will complete the hand
- Out
- A card that will improve your hand
- Outdraw
- To improve your hand from a losing hand to a winning one
- Overcard
- A card higher than any card on the board, or any card on the board higher than your pocket pair
- Overpair
- A card higher than any card on the board, or any card on the board higher than your pocket pair