What is maturity?
Maturity = Consistency + Improvement + Time
That's it. Plain and simple.
For years I've lived by another definition of maturity. My first boss and one of my good friends told me that maturity is not saying everything you think.
At the time, I thought, "wow, that's brilliant...and accurate." At the time, and even in present day I still say so many things that I think that should not be said out loud. There are so many of my own thoughts that I shouldn't give voice to. But there are also a lot of things I think that should be said that often go unsaid.
But the older I get, the more I feel maturity just comes with time and consistently improving who you are. Showing up on time. Being there for people repeatedly. Being loyal. Treating people better and better every time your interact with them.
I think not saying everything you think is something that comes with time and the consistency of getting better. If you're consistently improving as a person, then with time you will mature and grow.
Please note that I do not believe maturity has anything to do with whether you laugh at farts or crude jokes. Those are just funny.