The process of becoming less responsible and capable over time.

Often a trait of a middle-aged person who has given up on taking care of themselves - either due to personal choice or unforeseen, unfortunate circumstances. Someone who is immaturing was more capable and responsible as a young adult than at their current older age. They often displace their burdens on people who care about them.
She's 53 and immaturing; I find it hard to believe she was ever able to pay her own bills.

After Jeff lost the business he started immaturing, now I hear he's trying to move in with his kids.

My mother-in-law has been steadily immaturing since her divorce 15 years ago.

At the rate bob is immaturing, he'll likely be fired in 6 months.
by GummieGirl August 31, 2017
What one redneck says to another when he wants his chair back.
Hey, you done sat immature and I be wanting it back.
by Chase1204 April 14, 2008
An opinion. someone created it so others would act like them
Kid A: Dude i touched it and it got hard

Kid B: THATS WHAT SHE SAIDD!!!

Kid A: you're so immature

Kid B: F*ck you
by Hemesath May 13, 2010
Doing whatever it takes to make you happy and for some people, at least they're being who they are and not the stereotype of who they're supposed to be. Your inner child. Most people believe that age defines who you are and if you don't "act your age", you're immature. "Mature" people seem to be very depressed and settle for everything even if they don't want it.
Stuck up bitch: Why is that girl coloring in a spongebob coloring book? She's so immature.

Other person: At least she's doing what makes her happy, bitch.
by hofosho23 December 1, 2010
An overused term used by hypocrite teenagers (as in, 99%) to describe anyone or any opinion that they dislike.
Twilight fan #1: OMG that guy totally said Twilight is the boringest story EVER!!!

Twilight fan #2: OMG, he's so immature!!!
by lklkj98k November 2, 2009
-People who insult everyone who has a different opinion than theirs, usually with a personal, racial, or gay slur.
-People who become alcoholics and/or do drugs just because “it’s cool.”
-People who tend to be impulsive; an example of which, is a tendency to use unwanted physical contact on another person, or making statements in complete ignorance.
-People who act like a bitch because someone doesn’t want to do something for them.
-People who only ever need you to use you.
-People who behave like hypocrites too often.
-People who constantly bitch about their life when they have it better than who they are bitching to, or for attention.
-People who talk shit because they’re insecure about themselves, then get upset when the person finds out.
-People who offensively use words that are not interchangeable because they are too ignorant to educate themselves.
Your little brother may be immature
by therealdeal,itsbacon October 10, 2011