1. (n.) An onslaught; an assault; a beginning; as, the onset of a cold; an attack; a storming; especially, the assault of an army.

2. (n.) A setting about; a beginning.

3. (n.) Anything set on, or added, as an ornament or as a useful appendage.

4. (v. t.) To assault; to set upon.

5. (v. t.) To set about; to begin.