onset
1. [ noun ] the beginning or early stages
Synonyms: oncoming
Examples:

"the onset of pneumonia"

Related terms: start
2. [ noun ] (military) an offensive against and enemy (using weapons)
Synonyms: attack onrush onslaught
Examples:

"the attack began at dawn"

Related terms: operation strike fire charge bombing penetration counterattack diversion blitz banzai_attack surprise_attack ground_attack strafe assault military
Similar spelling:   on-site
  one-step
  Onstad
  one_shot
  Onstott
  onstage
  onside