define petri dish
Definition of PETRI DISH. 1. : a small shallow dish of thin glass or plastic with a loose cover used especially for cultures in bacteriology.2. ADVERTISEMENT.Julius R. Petri â 1921 German bacteriologist.. : a small shallow dish of thin glass or plastic with a loose cover used especially for cultures in bacteriology. 2. ADVERTISEMENT. Julius R. Petri â 1921 German bacteriologist.