Definitions for "dummy activity"
an activity that you add to the original activities list
Used to describe an activity which takes zero time to complete or has no work content.
Used in network diagrams to demonstrate where one activity is dependent on another. An activity of zero duration used to show a logical relationship in the arrow diagramming methods. Dummy activities are used when logical relationships cannot be completely or correctly described with regular activity arrows. Dummies are shown graphically as a dashed line headed by an arrow. (PMI)