An electrical network is a collection of elements through which current flows. The following definitions introduce some important elements of a network.
Branch
A branch is any portion of a circuit with two terminals connected to it. A branch may consist of one or more circuit elements

Node
A node is the junction of two or more branches (one often refers to the junction of only two branches as a trivial node).

Loop
A loop is any closed connection of branches

Mesh
A mesh is a loop that does not contain other loops

references :
FUNDAMENTALS OF ELECTRICAL ENGINEERING for Giorgio Rizzon