set upon (third-person singular simple present sets upon, present participle setting upon, simple past and past participle set upon)

1. To attack someone.

   I was set upon by a couple of young thugs.

   • 1984 August 18, Sue Hyde, “Gay Man Dies Following Queerbash Attack”, in Gay Community News, volume 12, number 6, page 2:

     O'Connell was walking with a friend when the pair was set upon by the teenagers. They beat O'Connell and knocked him to the ground.

   • 2019 February 27, Drachinifel, 31:46 from the start, in The Battle of Samar - Odds? What are those?‎^[1], archived from the original on 3 November 2022:

     With Gambier Bay and Hoel sinking and Roberts not much longer for this world, the Johnston is now set upon by four cruisers and a number of destroyers. The ship's crew patch holes as fast as they can, but the ship is literally gradually being taken apart by repeated salvos. The fact that this particular set of Japanese ships is STILL using armor-piercing instead of high explosive is the only saving grace.

2. To begin an activity; to embark upon a course of action.

   On receiving the letter, I immediately set upon writing a reply.

• set on

• onset