Electrically, a mesh is any closed path in a circuit. In other words, it is the wire and components that form a loop in a circuit. Generally, when one speaks of a mesh, they mean the smallest possible loop from a node, across a specific branch attached to that node, and returning to the original node. The term supermesh is often used to describe a mesh that contains two or more smaller meshes.

In Computer Graphics a mesh is a surface, usually piece-wise linear, describing the object to be rendered.
It's quite common, for instance, to describe a three-dimensional object as a set of vertices, and then defining the neighbourhood relations between them: in this way you get a mesh.

Another piece of information: at the last SIGGRAPH, a whole session was devoted to subdivision, an algorithm to iteratively refine a mesh, increasing the number of polygons belonging to the surface.

Mesh (?), n. [AS. masc, max, mscre; akin to D. maas, masche, OHG. masca, Icel. moskvi; cf. Lith. mazgas a knot, megsti to weave nets, to knot.]

1.

The opening or space inclosed by the threads of a net between knot and knot, or the threads inclosing such a space; network; a net.

A golden mesh to entrap the hearts of men. Shak.

2. Gearing

The engagement of the teeth of wheels, or of a wheel and rack.

Mesh stick, a stick on which the mesh is formed in netting.

Mesh, v. t. [imp. & p. p. Meshed (?); p. pr. & vb. n. Meshing.]

To catch in a mesh.

Surrey.

Mesh, v. i. Gearing

To engage with each other, as the teeth of wheels.