You guessed it. Selfactualization, self actualisation, and selfactualisation are all misspellings of Self-actualization. You would be amazed how easy it is to misspell it.

But, whether you spell it selfactualisation or selfactualization, the definition remains the same. Self actualisation is the act of doing what makes you feel fulfilled. This is not the same thing as personal growth or self improvement, both of which imply movement from a lower state to a higher state. Self-actualisation is the higher state.

Here are just a couple definitions of selfactualization:

"A musician must make music, an artist must paint, a poet must write, if he is to be at peace with himself. What a man can be, he must be. This is the need we may call self-actualization ... It refers to man's desire for fulfillment, namely to the tendency for him to become actually in what he is potentially: to become everything that one is capable of becoming ..."

This definition by Dr. Abraham Maslow, who first coined the term "self-actualization".

For everything there is a season,
And a time for every matter under heaven:
A time to be born, and a time to die;
A time to plant, and a time to pluck up what is planted;
A time to kill, and a time to heal;
A time to break down, and a time to build up;
A time to weep, and a time to laugh;
A time to mourn, and a time to dance;
A time to throw away stones, and a time to gather stones together;
A time to embrace, And a time to refrain from embracing;
A time to seek, and a time to lose;
A time to keep, and a time to throw away;
A time to tear, and a time to sew;
A time to keep silence, and a time to speak;
A time to love, and a time to hate,
A time for war, and a time for peace.