CO河牌冷跟注（彩虹面）（CO River Cold Call Rainbow）

Term Composition

This term is composed of four poker elements:

• CO: Cut Off, the position one to the left of the button (the second seat to the right of the dealer), a late position.
• River: The fifth community card betting round.
• Cold Call: Calling a raise without having any prior money in the pot (not having called or raised before). On the river, it usually means calling an opponent's bet.
• Rainbow: A board where all cards are of different suits on the flop or current community cards. On the river, it means all five community cards are of different suits.

Scenario Example

Suppose a hand reaches the river with the board ♠A ♥K ♣Q ♦J ♥10 — but this board has a flush possibility. A rainbow board requires all different suits, e.g., ♠A ♥K ♣Q ♦J ♠2 (only two spades, not a rainbow, and a flush draw is possible). A true rainbow board would be ♠A ♥K ♣Q ♦J ♠9 (all different suits). In this case, an early position player bets, the CO player calls instead of raising, and the board is a rainbow — this forms "CO River Cold Call Rainbow".

Strategic Implications

• Cold calling on the river from CO usually means a medium-strength hand, like one pair or two pair, with the player worried about being raised.
• Rainbow board eliminates flush draws, simplifying opponent range analysis — opponents are less likely to bluff bet with a flush draw. Therefore, a call is more likely to be a bluff catcher or a value showdown.
• This combined term is rarely used alone in actual play; it's more for recording hands or discussing specific scenarios.

Notes

This term is not an official poker noun but a descriptive phrase. Skilled players would use simpler expressions like "CO river call", and the rainbow nature is often implied.