to break without separation of parts; (cause to) become marked by lines that indicate a break: [no object]The window cracked when a rock hit it.[~ + object]The rock cracked the glass.
to break open or into many parts: [~ + object]cracked an egg into the bowl.[no object]The egg cracked when it hit the floor.
to break with a sudden, sharp sound: [no object]The wood in the fireplace cracked suddenly.[~ + object]I cracked a few pieces of wood and added them to the fire.
to (cause to) make a sudden, sharp sound; snap: [no object]The whip cracked and the lions roared.[~ + object]I cracked my knuckles nervously.
(of the voice) to break abruptly; change to the wrong pitch:[no object]The tenor's voice cracked on that high note.
to break down, esp. under severe psychological pressure:[no object]He finally cracked from all the stress.
to strike forcefully: [no object]His head cracked against the mantelpiece.[~ + object]She cracked his head with the vase.
to solve or reveal, esp. after much effort:[~ + object]to crack a murder case.
Informal TermsInformal. to break into (a safe, etc.):[~ + object]tried to crack the safe but couldn't.
Informal Terms[~ + object]Informal.
to open slightly, such as a door or window:Crack the windows and let's get some fresh air.
to open (a book) in order to study or read:It was a little late to be cracking the books.
crack down, to take severe measures, esp. in enforcing regulations: [no object]tried to crack down, but by then things had gotten out of control.[~ + down + on + object]a campaign to crack down on drug pushers.
[no object] to suffer a mental breakdown:He cracked up when his wife left him.
to (cause to) crash (an automobile or airplane): [no object]The car spun out of control and cracked up.[~ + up + object]cracked up his father's brand-new car.[~ + object + up]He cracked the car up the first time he drove it.
to (cause to) laugh hard without being able to stop: [no object]He cracked up at the sight of her in those old frumpy pajamas.[~ + up + object]That joke cracked up the audience.[~ + object + up]That joke cracked him up.
a break without separation of parts:[countable]a few cracks on the windshield.
Building a slight opening, as between boards in a floor:[countable]We plastered the cracks in the wall.
a sudden, sharp noise:[countable]The crack of a rifle shot rang out.
to break without complete separation of parts; become fissured:The plate cracked when I dropped it, but it was still usable.
to break with a sudden, sharp sound:The branch cracked under the weight of the snow.
to make a sudden, sharp sound in or as if in breaking; snap:The whip cracked.
(of the voice) to break abruptly and discordantly, esp. into an upper register, as because of weariness or emotion.
to fail; give way:His confidence cracked under the strain.
to succumb or break down, esp. under severe psychological pressure, torture, or the like:They questioned him steadily for 24 hours before he finally cracked.
Chemistryto decompose as a result of being subjected to heat.
Dialect Terms[Chiefly South Midland and Southern U.S.]to brag; boast.
Scottish Terms[Chiefly Scot.]to chat; gossip.
to cause to make a sudden sharp sound:The driver cracked the whip.
to break without complete separation of parts; break into fissures.
to break with a sudden, sharp sound:to crack walnuts.
to strike and thereby make a sharp noise:The boxer cracked his opponent on the jaw.
to induce or cause to be stricken with sorrow or emotion; affect deeply.
to utter or tell:to crack jokes.
to cause to make a cracking sound:to crack one's knuckles.
to damage, weaken, etc.:The new evidence against him cracked his composure.
to make mentally unsound.
to make (the voice) harsh or unmanageable.
to solve; decipher:to crack a murder case.
Informal Termsto break into (a safe, vault, etc.).
Chemistryto subject to the process of cracking, as in the distillation of petroleum.
Informal Termsto open and drink (a bottle of wine, liquor, beer, etc.).
crack a book,[Informal.]to open a book in order to study or read:He hardly ever cracked a book.
crack a smile,[Informal.]to smile.
crack down, to take severe or stern measures, esp. in enforcing obedience to laws or regulations:The police are starting to crack down on local drug dealers.
crack off, to cause (a piece of hot glass) to fall from a blowpipe or punty.
Naval Terms(of a sailing vessel) to sail in high winds under sails that would normally be furled.
Naval Terms(of a power vessel) to advance at full speed in heavy weather.
to suffer a mental or emotional breakdown.
to crash, as in an automobile or airplane:He skidded into the telephone pole and cracked up.
to wreck an automobile, airplane, or other vehicle.
to laugh or to cause to laugh unrestrainedly:That story about the revolving door really cracked me up. Ed cracked up, too, when he heard it.
crack wise,[Slang.]to wisecrack:We tried to be serious, but he was always cracking wise.
to begin moving or working; start:Let's get cracking on these dirty dishes!
to work or move more quickly.
a break without complete separation of parts; fissure.
Buildinga slight opening, as between boards in a floor or wall, or between a door and its doorpost.
a sudden, sharp noise, as of something breaking.
the snap of or as of a whip.
a resounding blow:He received a terrific crack on the head when the branch fell.
Informal Termsa witty or cutting remark; wisecrack.
a break or change in the flow or tone of the voice.
Informal Termsopportunity; chance; try:Give him first crack at the new job.
a flaw or defect.
Drugs, Slang TermsAlso called rock.[Slang.]pellet-size pieces of highly purified cocaine, prepared with other ingredients for smoking, and known to be especially potent and addicting.
Agriculture, Building[Masonry.]check1 (def. 46).
a mental defect or deficiency.
a shot, as with a rifle:At the first crack, the deer fell.
a moment; instant:He was on his feet again in a crack.
Slang Termsa burglary, esp. an instance of housebreaking.
British Terms[Chiefly Brit.]a person or thing that excels in some respect.
Slang Terms(vulgar). the vulva.
Scottish Terms[Chiefly Scot.]conversation; chat.
British Termsboasting; braggadocio.
Idiomsfall through the cracks, to be overlooked, missed, or neglected:In any inspection process some defective materials will fall through the cracks.Also, slip between the cracks.
first-rate; excellent:a crack shot.
with a cracking sound.
bef. 1000; Middle English crak(k)en (verb, verbal), crak (noun, nominal), Old English cracian to resound; akin to German krachen, Dutch kraken (verb, verbal), and German Krach, Dutch krak (noun, nominal)