Adam Makkai: Словарь американских идиом: 8000 единиц

[yours truly]{adv. phr.} 1. Signing off at the end of letters. •/ Yours truly, Tom Smith. / 2. I, the first person singular pronoun, frequently abbreviated as t.y. •/ As t.y. has often pointed out… / •/ T.y. is not really interested in the offer. /

[yum-yum]{interj.} , {informal}  — Used usually by or to children, to express great delight, especially in the taste of food. •/ "Yum-Yum! That pie is good!" /

[zero hour]{n.} 1. The exact time when an attack or other military action is supposed to start. •/ Zero hour for the bombers to take off was midnight. / 2. The time when an important decision or change is supposed to come; the time for a dangerous action. •/ It was zero hour and the doctor began the operation on the man. / •/ On the day of the championship game, as the zero hour came near, the players grew nervous. /

[zero in on]{v.} 1. To adjust a gun so that it will exactly hit (a target); aim at. •/ Big guns were zeroed in on the enemy fort. / •/ American missiles have been zeroed in on certain targets, to be fired if necessary. / 2. {slang} To give your full attention to. •/ The Senate zeroed in on the Latin-American problems. / •/ Let’s zero in on grammar tonight. /

[zip one’s lip]See: BUTTON ONE’S LIP.

[zone defense]{n.} A defense in a sport (as basketball or football) in which each player has to defend a certain area. •/ The coach taught his team a zone defense because he thought his players weren’t fast enough to defend against individual opponents. /

[zonk out]{v. phr.} , {slang} 1. To fall asleep very quickly. •/ Can I talk to Joe? — Call back tomorrow, he zonked out. / 2. To pass out from fatigue, or alcohol. •/ You won’t get a coherent word out of Joe, he has zonked out. /

[zoom in]{v. phr.} 1. To rapidly close in on (said of airplanes and birds of prey). •/ The fighter planes zoomed in on the enemy target. / 2. To make a closeup of someone or something with a camera. •/ The photographer zoomed in on the tiny colibri as it hovered over a lovely tropical flower. /