Less serious than getting together or dating. Spending time with someone in the context of friendship or in the context of casually exploring whether you like someone as just a friend or maybe more than a friend.
I'm gonna hang out with my best friend this weekend. We should hang out some time.
Comes from the formal meaning of "hang out": to protrude or stick out. Hence, the use of "out" for public. Not to be confused with "hang with", which is an umbrella term that includes socializing publicly or privately.
Friend: "Dude, you never hang out with me anymore."
You: "Not true: even though I don't get out of my house much, I still socialize with you on Facebook, which can be seen by other people."
Friend: "Touché."
Adolescent practice of spending aimless unstructured time together with someone else, often until both people get bored enough to have sex and go their separate ways. Often confused with dating.
I hang out with Julio all the time, but he never asks me out on a date.
Hanging out is when a person is spending time with one or more individuals. The people who are hanging out don't necessarily have plans or activities to perform. It is simply the act of being together for the purpose of socializing.
Dean and Ben love to hang out with Alana on weekends since they always have fun together.