crack verb

1 break

ADV. badly The dish had cracked quite badly. | slightly

2 become mentally ill

ADV. completely | finally The stresses of her job became too great and she finally cracked. | up He thought he'd never get through the ordeal without cracking up.

PHRASES crack under the pressure/strain, show signs of cracking He is under a lot of pressure but is showing no signs of cracking. PHRASAL VERBS crack down

ADV. hard

PREP. on to crack down hard on crime