step out on someone

step out

1. To leave some place. I stepped out for one minute and someone has already taken my seat! I'm sorry, the boss has stepped out, would you like to leave a message?
2. To go outside briefly. I'm just stepping out for a bit of fresh air.
3. To quit or withdraw from something. Now that the other candidate has stepped out, you two are the only ones left. We lost out best programmer when Jessica stepped out from the project.
4. To have sexual intercourse or relations with someone other than one's spouse. Usually followed by "on (someone)." It turns out that women are very nearly as like as men to step out on their partners. My dad stepped out on my mom when were just kids, and their marriage never recovered.
5. To go out with someone on a date. Usually followed by "with (someone)." It's really weird that my mom is stepping out with one of my friends. They've been stepping out for a couple of months now.
See also: out, step

step out on someone

in. to betray one’s lover by going out with someone else. Hank has been stepping out on Bess, and she doesn’t know it yet.
See also: on, out, someone, step