Middle English weren, "be clad or dressed in; carry or bear on the body for warmth, decency, ornament, etc.," from Old English werian "to clothe, put on, cover up," from Proto-Germanic *wasīn- (source also of Old Norse verja, Old High German werian, Gothic gawasjan "to clothe"), according to Watkins from a suffixed form of PIE *wes- (2) "to clothe," extended form of root *eu- "to dress."

The secondary sense of "consume by frequent or habitual use" (late 13c.) is from effect of continued use on clothes.

To wear down (transitive) "blunt the force of by steady resistance" is from 1843. To wear off "diminish by use, cease to have effect over time" is from 1690s. To wear out (transitive) "use till useless, waste or destroy by degrees" is by late 14c.; also intransitive "come to an end." To wear away "disappear gradually" is by mid-15c.

The Germanic forms "were homonyms of the vb. for 'prevent, ward off, protect' (Goth. warjan, O.E. werian, etc.), and this was prob. a factor in their early displacement in most of the Gmc. languages" [Buck].

In English it shifted from a weak verb (past tense and past participle wered) to a strong one (past tense wore, past participle worn) in 14c. on analogy of rhyming strong verbs such as bear and tear.

also careworn, "oppressed or burdened with cares," 1828, from care (n.) + worn.

"worn out; wasted or consumed by wear, use, or time," 1560s, from out- + worn.

"somewhat shabby from handling while on display," by 1811, from shop (n.) + worn (adj.). Shop-soiled in the same sense is by 1862. An earlier nonce-use was shop-rid (1610s), based on bed-rid.

"impaired by age," 1729, from time (n.) + worn (adj.).

"weary or worn with traveling," 1777, from way (n.) + worn (adj.).

"much affected by wear or use," 1620s, from well (adv.) + worn. The sense of "becomingly worn" (1814) is marked "rare."