a wide engine, for obvious reasons

One with its cylinders mounted horizontally, usually with two separate banks opposite each other but using a common crankshaft.

Form of engine design in which the cylinders are opposed horizontally, usually with an equal number on each side of the central crankshaft.

Engine design in which the pistons are horizontally opposed. Porsche, Subaru and some old VWs are common examples of flat engines.

A flat engine is an internal combustion engine with its pistons parallel to the ground. It can be an inline engine canted 90 degrees from straight up, and also can be a boxing engine sometimes referred to as a boxermotor, in which the cylinders are arranged in two banks on either side of a single crankshaft so that the motion of all the pistons is in a single plane.