TPMK is an abbreviation for top pair/middle or medium kicker, and refers to a pair made from the highest board card and one player's card. The player's other card, or kicker, is high but not the highest possible kicker.

Example (Texas Hold'em):

The player has a pair of kings with his king and the highest board card, so that's top pair. His highest kicker is the queen, so he's not holding the highest possible kicker. Hence, it is possible that the opponent is holding a pair of kings with a higher kicker, namely an ace.

Related topics:

Top pair, TPTK