The capacity of an object to do work. Forms of energy include:

• Potential or stored energy
• Kinetic or working energy, computed as half an object’s mass multiplied by square of its velocity.

Related terms in Physics Terms for Fly Casting: Speed, Velocity, Acceleration, Positive Acceleration, Negative Acceleration / Deceleration, Constant Acceleration

From the FFI Fly Casting Definitions (2025 Edition), reproduced with attribution to Fly Fishers International.