In thermodynamics

Thermodynamics

Thermodynamics is a physical science that studies the effects on material bodies, and on radiation in regions of space, of transfer of heat and of work done on or by the bodies or radiation...

, work performed by a system

System

System is a set of interacting or interdependent components forming an integrated whole....

 is the energy

Energy

In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...

 transferred to another system that is measured by the external generalized mechanical constraints on the system. As such, thermodynamic work is a generalization of the concept of mechanical work

Mechanical work

In physics, work is a scalar quantity that can be described as the product of a force times the distance through which it acts, and it is called the work of the force. Only the component of a force in the direction of the movement of its point of application does work...

 in mechanics. Thermodynamic work encompasses mechanical work plus many other types of work. It does not include energy transferred between systems by heat, as heat is modeled distinctly in thermodynamics.