1. To tinker or fiddle with something. Hey, don't mess about with the thermostat—it needs to stay at 68 degrees. Grandpa's still messing about with that old radio, but I doubt he'll get it to work again.

2. To test or use something in order to learn more about it. I'm messing about with a different platform for my blog, and I can't decide if I like it or not.

3. To engage in aimless recreation or frivolous time-wasting with someone or something; to fool about with someone or something. Quit messing about with the dog and work on your book report already, Scotty!

4. To tease or play a prank on someone, often by trying to get them to believe something that is not true. Come on, stop messing about with me. There's no such thing as ghosts.

5. To engage in casual sexual encounters with someone. Betsy and I are just messing about with each other, which is great because I don't want a serious relationship anyway.