Software Architect's Handbook

Dependency

A dependency is a type of relationship between UML elements, such as classes, in which one element requires, needs, or depends on another element. The dependency is sometimes referred to as a supplier/client relationship because the supplier provides something to the client. The client is either semantically or structurally dependent on the supplier. A dependency may mean that changes to a supplier may require changes to a client.

In an association, one class may have a reference to the other as a member variable. A dependency relationship is slightly weaker. For example, a dependency may exist because a return type or parameter for a method in one class references another class:

A dependency is graphically represented by a dashed ...