A Use relationship indicates that one element requires another to perform some interaction. The Use (or Usage) relationship does not specify how the target supplier is used, other than that the source client uses it in definition or implementation. A Use relationship is a sub-typed Dependency relationship.
OMG UML Specification
The OMG UML specification (UML Superstructure Specification, v2.1.1, p. 138) states:
A usage is a relationship in which one element requires another element (or set of elements) for its full implementation or operation. In the metamodel, a Usage is a Dependency in which the client requires the presence of the supplier.