What is Happiness????

Is it something materialist or is it spiritual?
Can we get happiness whenever we want or is it something uncontrollable?
Can we retain it for longer period of time or it's just a matter of time that it vanishes?
Why the word happiness, why can't it be called contentment or pleasure or goal or anything u can think of?
Why is it that humans crave for happiness when they know that it's shortlived?
Can't we remain constant - i.e with not much outburst of joy or sorrow?
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it's an endless Q.. that remains