1. (noun)erosion, eroding, eating away, wearing, wearing away (geology) the mechanical process of wearing or grinding something down (as by particles washingover it)
2. (adj)wear, wearing the act of having on your person as a covering or adornment "she bought it for everyday wear"
3. (adj)exhausting, tiring, wearing, wearying producing exhaustion "an exhausting march"; "the visit was especially wearing"