adverb
in many ways; on many levels; in various respects
Used to describe something that applies or is true across multiple aspects, fields, or dimensions. Often appears in formal or analytical contexts.
この計画は多方面に影響を与えるだろう。
This plan will have an impact on many levels.
彼は多方面に才能を発揮している。
He displays his talents in various fields.
Compound of 多 (many) + 方面 (direction, field) + adverbial particle に. The exact historical derivation is straightforward; the expression is a modern adverbial formation.