onset Meaning, Definition & Usage

  1. noun the beginning or early stages
    oncoming.
    • the onset of pneumonia
  2. noun (military) an offensive against an enemy (using weapons)
    attack; onrush; onslaught.
    • the attack began at dawn

WordNet

On"set` noun
Etymology
On + set.
Definitions
  1. A rushing or setting upon; an attack; an assault; a storming; especially, the assault of an army. Milton.
    The onset and retire Of both your armies. Shak.
    Who on that day the word of onset gave. Wordsworth.
  2. A setting about; a beginning. Obs. Shak.
    There is surely no greater wisdom than well to time the beginnings and onsets of things. Bacon.
  3. Anything set on, or added, as an ornament or as a useful appendage. Obs. Johnson.
On"set` transitive verb
Definitions
  1. To assault; to set upon. Obs.
  2. To set about; to begin. Obs. Carew.

Webster 1913