Blemisher

Part of speech: noun

Definitions

1. Something or someone that mars, stains or spoils the appearance or perfection of a thing
2. A person or object that causes a flaw, mark or imperfection that damages how something looks or is regarded
3. Anything that disfigures or tarnishes a surface, reputation or otherwise flawless condition

Etymology: "Blemisher" is a plain formation: the noun "blemish" with the agent suffix "-er" attached, giving a sense of one who or that which blemishes. "Blemish" itself comes from Old French "blemir", meaning to make pale or injure, which is the root of the idea of marring something's surface or reputation. Adding "-er" turns that action into a doer or cause, so a blemisher is anything that spoils or mars. The word is rare, and most of its usefulness lies in its transparency: once you know "blemish", its meaning follows directly from the suffix. It is the kind of coinage English speakers can build on demand, which is why it appears more often in informal or descriptive writing than in dictionaries.