思いっ切り — “to one's heart's content, as hard as one can, with all one's might”
思いっ切り (read おもいっきり) means to one's heart's content, as hard as one can, with all one's might. It appears on the JLPT N2 vocabulary list and is a adverb.
Reading
おもいっきり
Meaning
to one's heart's content, as hard as one can, with all one's might