If someone is patronizing, they talk to you as if you were smaller, younger, or slower than they are. The words may sound kind — “let me explain it in simple terms” — but the feeling underneath is “I am above you.” People bristle at it, because it does not only disagree; it looks down.

This is the unkind sense of the verb patronize. Though actually, that verb has another, older, perfectly polite sense, especially in American English: to patronize a shop is to go there as a customer. So “She patronized the café for years” may mean she ate there, not that she talked down to the waiter. The adjective patronizing, used of a person or a tone, almost always means the rude talking-down. British spelling is often patronising, with an s.

The rude sense grew from the old social picture of a patron: someone higher, handing down help. Help from above can turn into a smile from above.