Martini UK /mɑːˈtiːni/US /mɑɹˈtini/noun 3forms 1phrases 1 noun3 •A brand of Italian vermouth available in several versions, from the Martini & Rossi company. •A type of rifle using similar features.Now the butt of a Martini in the small of your back hurts a great deal — 1888 •(no longer used) A breech mechanism for a rifle. formsMartinis Phrases with Martini three-martini lunchA leisurely, expensive midday meal associated with drinking, which is tax-deductible because business is discussed.