tell on

1 to act upon (a person or a person's feelings) so as to cause a response the pressure of final exams is beginning to tell on the students in the dorm Synonyms impact, impress, influence, move, reach, strike, sway, {h,1}affect (on), touchRelated Words carry away, dazzle, enrapture, entrance, enthrall (or enthral), ravish, transport; bias, color; inspire, stir; engage, interest, involve, penetrate, pierce; afflict, agitate, bother, concern, discomfort, discompose, disquiet, distress, disturb, fluster, harass, harry, perturb, pester, plague, smite, strain, stress, trouble, try, upset, worry, wring; allure, attract, bewitch, captivate, charm, enchant, fascinateNear Antonyms bore, jade, pall, tire, weary; underwhelm

2 to give information (as to the authorities) about another's improper or unlawful activities in that neighborhood, you wouldn't even think about telling on the drug dealers Synonyms fink, grass (on) [British slang], inform, rat (on), sing, snitch, split (on) [British], squeak, talk, squeal (on)Related Words betray, give away, turn in; backstab, cross, double-cross, sell (out), two-time; blab, tattle; tip (off)