The title of "Hanging Fire" may seem disconnected with the poem itself: what does a phrase from gun jargon have to do with a poem spoken by a teenage girl? That's a good question. The first thing to know is that the phrase describes a dangerous gun-related situation: when there's a delay between the triggering of a gun and the gun's actual ignition. In the poem, the phrase "hanging fire" works metaphorically, as there are no actual guns in the poem. It refers not to that dangerous pause in gun use, but to that precarious time of a person's life between childhood and adulthood. We're all "hanging fire" when we're teens.
Title: Lorde titles her poem with a gun metaphor, and thus we know that she's up to something serious. Being a teenager isn't all about braces and pimples; it can be a really dangerous time. By titling her poem "Hanging Fire," Lorde acknowledges the direness of her speaker's worried—and worrisome—situation.