A break or fissure

verb

1. To make a very sharp explosive sound

   "The whip cracks through the air."

2. To break, split, or snap apart

   "The statue cracked when she dropped it."

3. To lose control or effectiveness under pressure
4. To fail in tone

   "His voice cracked."

5. To go or travel at good speed
6. To break so that fissures appear on the surface

   "crack a mirror"

7. To break with a sudden sharp sound

   "crack nuts"

8. To tell especially suddenly or strikingly

   "crack a joke"

9. To strike with a sharp noise rap

   "then cracks him over the head"

10. To puzzle out and expose, solve, or reveal the mystery of

    "crack a code"

11. To break into

    "crack a safe"

12. To open slightly

    "crack the throttle"

13. To break through (something, such as a barrier) so as to gain acceptance or recognition

    "… on track to crack Hollywood after landing a big screen role."

14. To show or begin showing (a smile) especially reluctantly or uncharacteristically
15. To impair seriously or irreparably wreck

    "crack an opponent's courage"

16. To destroy the tone of (a voice)
17. Disorder, craze

    "Worry had cracked his otherwise cheerful disposition."

18. To interrupt sharply or abruptly

    "The criticism cracked our complacency."

19. To cause to make a sharp noise

    "cracks his knuckles"

20. To break up (chemical compounds) into simpler compounds by means of heat

noun

1. A loud roll or peal

   "a crack of thunder"

2. A sudden sharp noise

   "the crack of rifle fire"

3. A sharp witty remark quip
4. A narrow break fissure

   "a crack in the ice"

5. A narrow opening

   "Leave the door open a crack."

6. A weakness or flaw caused by decay, age, or deficiency unsoundness
7. A broken tone of the voice
8. Crackpot
9. Moment, instant

   "the crack of dawn"

10. Housebreaking, burglary
11. A sharp resounding blow

    "gave him a crack on the head"

12. An attempt or opportunity to do something

    "her first crack at writing a novel"

13. A potent form of cocaine that is obtained by treating the hydrochloride of cocaine with sodium bicarbonate to create small chips used illicitly for smoking

adjective

1. Of superior excellence or ability

   "a crack marksman"

noun

1. An infant subjected to prolonged exposure to crack cocaine in the mother's womb

verb

1. To take positive regulatory or disciplinary action

noun

1. A house or apartment where crack is made, sold, or used

noun

1. Crash, wreck

   "an automobile crack-up"

2. A mental collapse nervous breakdown

   "his wife's death brought on his crack-up"

3. Collapse, breakdown

verb

1. Praise, tout

   "wasn't all that it was cracked up to be"

2. To damage or destroy (a vehicle) by crashing

   "crack up a car"

3. To cause to laugh out loud

   "that joke really cracks him up"

4. To damage or destroy a vehicle (as by losing control)

   "cracked up on a curve"

5. To laugh out loud

idiom

1. To smile

   "I tried to get him to laugh, but he never even cracked a smile."

phrasal verb

1. To enter or get started in (something, such as a profession)

   "It's not easy to crack into professional football."