na-adjective
external; outward; in appearance
Describes something based on its outward form or appearance, often contrasting with inner substance. Used in formal or analytical contexts.
外形的な特徴だけで判断してはいけない。
You shouldn't judge based solely on outward characteristics.
この書類は外
This document looks fine on the surface, but we need to check the content carefully.
形式的 means 'formal' or 'perfunctory', focusing on following prescribed forms. 外形的 emphasizes the outward appearance or shape rather than the inner substance.
Compound of 外形 (external form) + 的 (-like, adjectival suffix). The exact historical derivation is straightforward; the word follows a common pattern for forming adjectival nouns.