To be content and satisfied with your life and surroundings, even when something which may destroy these conditions is imminent. Generally requires the ability to be able to not be concerned about relative dangers nor your shortcomings in life, unless you happened to have achieve most your goals, in which case complacency will come. It is a good feeling to be complacent but difficult to achieve for some people. To be complacent all the things you want to have must overlap, if you desire something which you do not have you will not be fortunate enough to achieve this feeling. If you feel a genuine happiness it is accompanied by complacency.
"I would be complacent if I could convince a girl to go ass to mouth."
"Complacency seems so simple, like, fuck it
let me be the one you fight and call Mr. Right"
To be satisfied with ones self.
The kid was complacent with his small little trouble free world.
The hippies and lazy teenagers were complacent, complaining but never doing anything about it, never realizing they were part of the problem.
The complacent protestor held up a sign and screamed chants, complaining a lot, but never took any positive action to make a change.
The old guy became complacent and got a bunch of diseases because he didn't take care of himself, lacking the motivation to do anything with his waning years.
A state of mind that everyone in the world is trapped in except for kids and teenagers, hippies, protestors, old people, and anyone who ever bothered to follow their dreams(and succeeded).
If being bitter and complacent is what it means to grow up, then let me stay immature forever.