na-adjective
Describes something having many sides, aspects, or uses; often applied to people, approaches, or objects.
彼は多面的な才能を持っている。
He has multifaceted talents.
この問題は多面的に検討する必要がある。
This problem needs to be examined from multiple angles.
Compound of 多面 (many sides) + 的 (-like, -ic). The exact historical derivation is uncertain, but the word follows a common pattern for forming adjectival nouns from Sino-Japanese roots.