A type of sausage, often served in a bun or on a stick. The term is a wasei-eigo combination of 'Frankfurt' and 'sausage'.
wasei (Japanese coinage from German), from Frankfurt · wasei-eigo (Japanese-coined English), from sausage
朝ごはんにフランクフルトソーセージを焼いた。
I grilled a frankfurter for breakfast.
I bought a frankfurter at the food stall.