onset

noun

1. the beginning or early stages

- the onset of pneumonia

Similar word(s): oncoming

Definition categories: event, start

2. (military) an offensive against an enemy (using weapons)

Similar word(s): attack, onrush, onslaught

Definition categories: act, operation

verb

1. (obsolete) To assault; to set upon.

2. (obsolete) To set about; to begin.