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: FAIL: such as
a: to lose control or effectiveness under pressure —often used with up
The stress was so great that she started to crack up.
b: to fail in tone
His voice cracked.

4: to go or travel at good speed —usually used with on
The steamboat cracked on.