Definition from Wiktionary, the free dictionary
open fire (third-person singular simple present opens fire or rarely open fires, present participle opening fire or sometimes open firing, simple past and past participle opened fire or sometimes open fired)
- (idiomatic) To begin firing (weapons) at something or someone.
- In warfare, whoever opens fire first has a greater chance of victory.
to begin firing at something or someone
- uncovered fire
- We roasted chestnuts over an open fire.