This is the 4240th most frequent German word.
coolen
"Coolen" is the German verb meaning "to cool" or "to cool down."
'Coole' is used here as an adjective in the feminine accusative form to describe the jacket.
Er trägt eine coole Jacke.
He wears a cool jacket.
'Coole' functions as an adjective in the feminine nominative singular form to describe the noun idea.
Das ist eine coole Idee.
That is a cool idea.
'Cooles' is the neuter accusative form of the adjective, modifying the noun car.