na-adjective, noun
Describes a person's physique or appearance as large, muscular, and physically impressive. Often used for men with a commanding, sturdy build. Not used for abstract greatness.
彼は魁偉な体格の持ち主だ。
He has a brawny physique.
その俳優は魁偉な風貌で悪役を演じることが多い。
That actor often plays villains because of his imposing appearance.
The word is composed of the kanji 魁 (large, leading) and 偉 (great, admirable). The exact historical derivation is uncertain, but the combination naturally conveys an imposing physical presence.