hair-trigger /ˈhɛɹˌtɹɪ.ɡɚ/adjective 2noun 2forms 2 adjective2 •Unstable; in a situation that could be worsened by the slightest mistake. •Easily angered; having a short temper."Gus," the latter began, "am I right in assuming that you possess a reasonable amount of influence with that hair-trigger partner of yours, Live Wire Luiz?" — 1922 noun2 •A trigger that will set off a firearm when even a very small pressure is applied.[…]the hunter brings the sight of his rifle to bear; lightly and delicately his finger presses upon the hair-trigger. — 1847 •(figurative) Any unstable situation. formshair triggers · hair-triggers