the.com/c clamp

means A C-shaped clamping tool with a screw-driven jaw, used to hold materials tightly together while glue dries, metal gets welded, or pieces get worked on.

from The name is pure plain description — the tool's frame is shaped like the letter C, open on one side with a threaded screw closing the gap. It's sometimes called a G-clamp in Britain, because with the handle sticking out, the silhouette reads more like a G than a C. Either way, the name is just the alphabet doing honest work.