A terminal fitting (60) includes a stabilizer (65) arranged on a first surface of a body (61) and configured to enter a guide groove (23) if the terminal fitting is in a proper insertion posture while restricting insertion by contacting a contact surface (24B) if the terminal fitting (60) is in an inverted insertion posture opposite to the proper insertion posture. The terminal fitting (60) includes a rattling preventing protrusion (66) arranged on a second surface of the body (61) opposite to the first surface and at a position overlapping the stabilizer (65) in a front-rear direction and capable of contacting facing upper wall surfaces (27) of a cavity (21) with the terminal fitting held in the inverted insertion posture and the stabilizer (65) held in contact with the contact surface (24B).