Under the Gun
The position directly left of the Big Blind. This player has to perform the first action of the hand (bet, Call, Fold).
Underpair
If the rank of the cards that form your Pocket Pair is lower than any card on the table, you hold a Underpair. For example: You hold 44 and the Board shows 69K. Also see Overpair.
Up
Used if you have Two Pairs to denote the higher Pair. A JJ844 would be called "Two Pairs, Jack up", because the rank of the lower Pair is only of importance if your opponent also has "Two Pairs, Jack up".
Upcard
A card that is dealt face up. Also see Board or Community Cards.
UTG
Abbreviation for Under the Gun.