The word 'threadbare' is a transparent English compound formed from two native Old English elements. It literally describes fabric that has become so worn with use that the underlying threads are exposed and visible, leaving the material thin and meager. This vivid physical imagery was first recorded in the late 14th century. By the late 16th century, the term's meaning had extended metaphorically to describe ideas, jokes, or arguments that have been overused to the point of becoming insubstantial and lacking originality, much like worn-out cloth.

Structure: thread + bare - thread: From Old English þrǣd, meaning a fine cord of spun fibers. In this compound, it functions as a noun denoting the material component of fabric. - bare: From Old English bær, meaning uncovered, naked, or meager. In this compound, it functions as an adjective describing the state of the 'thread'.