[ace in the hole]{n. phr.} 1. An ace given to a player face down sothat other players in a card game cannot see it. •/When the cowboy bet allhis money in the poker game he did not know that the gambler had an ace in thehole and would win it from him./ 2. {informal} Someone or somethingimportant that is kept as a surprise until the right time so as to bringvictory or success. •/The football team has a new play that they are keepingas an ace in the hole for the big game./ •/The lawyer’s ace in the hole wasa secret witness who saw the accident./ Compare: CARD UP ONE’S SLEEVE.

[Achilles' heel]{n. phr.}, {literary} A physical or psychologicalweakness named after the Greek hero Achilles who was invulnerable except for aspot on his heel. •/John’s Achilles' heel is his lack of talent with numbersand math./

[acid head]{n.}, {slang} A regular user of LSD on whom thehallucinogenic drug has left a visible effect. •/The reason John acts sofunny is that he is a regular acid head./

[acid rock]{n.}, {slang} A characteristic kind of rock in whichloudness and beat predominate over melody; especially such music as influencedby drug experiences. •/John is a regular acid rock freak./

[acorn] See: GREAT OAKS PROM LITTLE ACORNS GROW.

[acoustic perfume]{n.}, {slang} Sound for covering up unwantednoise, such as music over loudspeakers in a noisy construction area. •/Let’sget out of here — this acoustic perfume is too much for my ears./

[acquire a taste for]{v. phr.} To become fond of something; get tolike something. •/Jack acquired a taste for ripe cheeses when he went toFrance./

[across the board]{adv. phr.} 1. So that equal amounts of money are