activity

The smallest self-contained unit of work used to define the logic of a project.

In general, activities share the following characteristics: a definite duration, logic relationships to other activities in a project, use resources such as people, materials or facilities, and have an associated cost.

SOURCE: welcom.com

An element of work performed during the course of a project. An activity normally has an expected duration, an expected cost, and expected resource requirements.

Activities are often subdivided into tasks.

SOURCE: apm.com