The term 'PAY THE TAB' is a phrase used to describe the act of paying for a group's expenses. The crossword solutions TREAT (5 letters) and SETTLEUP (8 letters) are both synonyms for this phrase. TREAT is a verb meaning to pay for someone else's expenses, while SETTLEUP is a noun that refers to the act of settling a bill or debt. Both words can be used interchangeably with PAY THE TAB to describe the same action.