The compound adjective 'well-worn' is a straightforward combination of two native English elements. The adverb 'well,' with its Old English origin meaning "thoroughly," is used here as an intensifier. It modifies the participial adjective 'worn,' descended from the Old English verb for wearing away or using. The literal logic is "thoroughly worn (by use)," which first described physical objects like paths or clothing. This concrete meaning was then extended metaphorically to describe non-physical things like phrases or ideas that have been used so extensively they have become familiar to the point of being stale or clichéd, demonstrating a classic path of semantic evolution from the physical to the abstract.

Structure: well (thoroughly) + worn (past participle of 'wear') - well: From Old English wel, meaning "in a good way, satisfactorily, thoroughly." It functions as an intensifying adverb in this compound. - worn: From Old English woren, the past participle of werian (to wear). It functions as the core adjective describing the state resulting from the action of wearing.