A person or thing that is seminal and influential.
The front part of a semi-trailer type truck, i.e., the tractor to which the trailer part attaches.
A military or heavy construction vehicle.
The initial agent that is the cause of all things.
A machine, such as a water wheel or steam engine, that receives and modifies energy as supplied by some natural source or fuel and transforms it into mechanical work
An individual who abuses or exceeds his/her authority over others, frequently in petty ways.