crack

noun

• 1a line on the surface of something along which it has split without breaking apart:a hairline crack down the middle of the glass
• a narrow space between two surfaces which have broken or been moved apart:he climbed into a crack between two rocks the door opened a tiny crack
• a vulnerable point; a flaw:the company spotted a crack in their rival’s defences

• 2a sudden sharp or explosive noise:a loud crack of thunder
• a sharp audible blow:she gave the thief a crack over the head with her rolling pin
• a sudden harshness or change in pitch in a person’s voice:the boy’s voice had an uncertain crack in it

• 3 informal a joke, typically a critical or unkind one: he knew about the gossip and would make the odd crack

• 4 (also craic) [mass noun] chiefly Irish enjoyable social activity; a good time:he loved the crack, the laughing
• [count noun] Scottish & Northern English a conversation:they are having a great crack about shooting

• 5 [in singular] informal an attempt to achieve something:I fancy having a crack at winning a fourth title
• a chance to attack or compete with someone:he wanted to have a crack at the enemy

• 6 (also crack cocaine) [mass noun] a potent hard crystalline form of cocaine broken into small pieces and inhaled or smoked: he uses crack and cocaine [as modifier]:a crack dealer

verb

• 1break or cause to break without a complete separation of the parts: [no object]:the ice all over the bog had cracked [with object]:take care not to crack the glass
• break or cause to break open or apart: [no object, with adverbial]:a chunk of the cliff had cracked off in a storm figurativehis face cracked into a smile [with object]:she cracked an egg into the frying pan
• [with object] break (wheat or corn) into coarse pieces.
• give way or cause to give way under torture, pressure, or strain: [no object]:the witnesses cracked and the truth came out [with object]:no one can crack them—they believe their cover story

• 2make or cause to make a sudden sharp or explosive sound: [no object]:a shot cracked across the ridge [with object]:he cracked his whip and galloped away
• [no object] knock hard against something:she winced as her knees cracked against metal
• [with object] hit (someone or something) hard:she cracked him across the forehead
• [no object] (of a person’s voice) suddenly change in pitch, especially through strain:‘I want to get away,’ she said, her voice cracking

• 3 [with object] informal find a solution to; decipher or interpret:the code will help you crack the messages
• break into (a safe).

• 4 [with object] tell (a joke): he cracked jokes which she didn’t find very funny

• 5 [with object] decompose (hydrocarbons) by heat and pressure with or without a catalyst to produce lighter hydrocarbons, especially in oil refining: catalytic cracking increases gasoline yields

adjective

• very good or skilful:he is a crack shot crack troops