A turnoff is a situation or thing that causes disinterest, boredom, annoyance, or repulsion. It can refer to something that discourages people from continuing with an activity or pursuing further involvement in it. For example, if someone finds the behavior of another person to be off-putting or unappealing, they may say "That's a real turnoff." In other words, it is something that makes them lose interest and want to avoid it.