• FORENSIC (adjective). The adjective FORENSIC has 1 sense: 1. of, relating to, or used in courts of law or public debate or argument. Familiarity information: FORENSIC used as an adjective is very rare. FORENSIC (adjective). The adjective FORENSIC has 1 sense: 1. of, relating to, or used in courts of law or public debate or argument. Familiarity information: FORENSIC used as an adjective is very rare.