"Hanging Fire" is the title of the poem, and it comes from the lingo of weaponry. ("Hang Fire" is also the title of a pretty '80s-tastic Rolling Stones song). In case gunnery is not your field of expertise, we'll explain it: a "hang fire" refers to an unplanned delay between the triggering and the ignition of a gun. It's a moment of pause between pulling the trigger of a gun and its actual firing.
Audre Lorde's use of the phrase "hanging fire" in the poem's title is metaphorical. The poem's not about guns, or gun malfunctions, but about adolescence. Think about the teenage years as a time of "hanging fire"—a dangerous time between childhood and adulthood, a long and risky pause. In fact, the phrase has entered conversational English to signify a delay in progress. Yep, it sure sounds like a perfect encapsulation to teenagehood to us.
Even though "hanging fire" is not just relegated to weaponry jargon, the phrase still retains that connection to guns. And by titling her poem with a gun metaphor, Lorde is alerting us to the danger in this poem. There's a threat underlying the speaker's teenage anxieties. And there's a threat in the repeated lines "and momma's in the bedroom / with the door closed." Adolescence is not all braces and dances; it's a tough, even dangerous time for lots of teens.