a clamp in the shape of a C
a curved metal clamp shaped like a reversed letter C that extends out from a workbench
C-clamps utilize a vise-like handle and grip to support workpieces for light service and industrial applications. Some models offer positive trigger action for fast opening and closing.
C-clamps range in size from 1 to 8 inches long, with throat depths from 1 to 3 1/4 inches (although special deep-throat C-clamps also are available). They're essential for small- and medium-size gluing jobs and a variety of other holding tasks. Home Improvement Encyclopedia
a clamp with a C-shaped frame and an adjustable screw used for holding objects in place or together.
C shaped metal clamp that has an adjustable threaded screw that bridges the open part of the C and clamps onto a surface.
The C-clamp or G-cramp is a type of clamp device typically used to hold a wood or metal workpiece. These clamps are called "C" clamps because of the C shaped frame and are often used in, but are not limited to, carpentry and welding.