Noah Webster's Dictionary 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.

Multi-Version Concordance Onset (1 Occurrence) Acts 14:5 And when there was made an onset both of the Gentiles and of the Jews with their rulers, to treat them shamefully and to stone them, (ASV)