This is the 534th most frequent Finnish word.
päättänyt
"Decided"
Here, 'päättänyt' is the past participle of 'päättää', used together with 'olen' (I have) to indicate a decision made prior to the present moment.
Olen päättänyt lopettaa tupakoinnin.
I have decided to quit smoking.
In this sentence, 'päättänyt' is utilized with 'oli' (he/she had) to signify an action (the deciding) that occurred before another past event.
Hän oli päättänyt lähteä aikaisin töistä.
He had decided to leave work early.
In this example, 'päättänyt' indicates a personal decision or resolution that has been arrived at and resolved upon.