Pond

A pond is typically a man made body of water smaller than a lake. However the difference between a pond and an artificial lake is subjective. They are both formed by ponding water. Ponds can be made by excavating a hollow in which water may lie, filling an existing depression with groundwater or water diverted from a stream, or by forming a dam to impound the water in a valley.

The techniques may be combined to form a reservoir in flat country by enclosing an area with an embankment. Such a pond, unless very small, is usually called a reservoir. In some cultures, the meaning has been extended to include small bodies of water impounded naturally. (Oxford English Dictionary)

Scientifically, a pond is any man made body of water where light is found in the entire pond body of water. A lake is any body of water that has a profundal zone; there is as limit of effective light penetration for organisms.