na-adjective
temporary; transitory; short-lived
Describes a state or situation that is not permanent and will change after a limited time. Often used in formal or written contexts.
この問題は一時的なものだと思う。
I think this problem is temporary.
彼は一時的な流
He is not swayed by short-lived trends.
臨時 means 'extraordinary' or 'special' and often implies a provisional arrangement, whereas 一時的 simply means 'temporary'.
Compound of 一時 (いちじ, 'one time, a short time') + 的 (てき, '-like, -ish'), forming an adjectival noun meaning 'temporary'.