prefix
Prefix used before nouns to express large scale, intensity, or importance. Often carries a colloquial or emphatic tone.
彼は偉い学者だ。
He is a great scholar.
今日は偉い人に会った。
I met a big shot today.
Adjective meaning 'great', 'admirable', or 'terrible'. The prefix 偉 is attached directly to nouns, while 偉い modifies nouns as a full adjective.
Derived from the adjective 偉い (えらい, 'great'). The prefix form is used directly before nouns.