Something off-putting makes you pull back. You do not like it, or it looks unattractive, or it makes you not want to go nearer — a smell, a rude manner, a huge price, a website that shouts at you. It comes from put off in the sense “make someone not want to do something,” not the other put off that means “leave it until later.” Though actually, it is often milder than “horrible”: the thing can be fine for someone else, but for you it gets in the way. It is ordinary English, a little informal, used about people, places, and things.

讓人卻步；倒胃口