crack

• fracture, split; loud sharp noise; blow; witty remark; form of cocaine
split, fracture; make a loud sharp noise; whip; open a little
excellent, first-rate
if something cracks or if you crack it, it becomes slightly damaged, with lines appearing on its surface.
if someone cracks, they come close to having a nervous breakdown or they become mentally ill because of stress; an informal use.
if you crack a problem or a code, you solve it, especially after a lot of thought.
if you crack a joke, you tell it.
a crack is a very narrow gap between two things.
a crack is also a line appearing on the surface of something when it is slightly damaged or partly broken.
a crack is also a sharp sound like the sound of something suddenly breaking.
a crack is also a slightly rude or cruel joke.
a crack soldier or sportsman is highly trained and very skilful.
crack is a form of the drug cocaine which has been purified and made into crystals.
see also cracked.
if you do something at the crack of dawn, you do it very early in the morning.
if you have a crack at something, you make an attempt to do it; an informal expression.
if people in authority crack down on someone or something, they enforce the rules or laws against it.
if someone cracks up, they are under such a lot of emotional strain that they become mentally ill; an informal expression.