noun
1. : powerhouse 1 a
2. : an engine and related parts (as carburetion system, ignition apparatus, transmission) supplying the motive power of a self-propelled vehicle
an aeroplane can be considered as being divided into two main parts, the power plant and the airframe — Manual of Seamanship
a 90- or 99-inch wheelbase car … tough enough to take any power plant up to 450 horsepower — Les Nehamkin