the.com/dead weight

means The heavy, inert part of a load that has to be carried or moved but does none of the work itself — and by extension, a person or burden that drags down an effort without helping it.

from A straightforward compound from 'dead' (lifeless, inert) plus 'weight,' first used literally in shipping and engineering to mean the weight of a load itself, as opposed to the force needed to move it — hence terms like 'deadweight tonnage' for a ship's carrying capacity. The figurative sense, for a useless or burdensome person or factor, grew naturally out of this: something that adds mass and resistance but no motion or benefit of its own.