na-adjective, noun
selfishly as one pleases; willfully as one pleases
Describes acting entirely according to one's own desires without regard for others. Often used in negative contexts.
彼は気まま放題に振る舞って、周りを困らせている。
He behaves as selfishly as he pleases, causing trouble for those around him.
気まま放題な生活を送るのも、時には必要だ。
Sometimes it's necessary to live as freely as one pleases.
Compound of 気まま (selfish, willful) and 放題 (as much as one likes). The exact historical derivation is uncertain.