mega

The term 'mega' is a direct borrowing from the ancient Greek adjective 'μέγας' (megas), meaning 'great' or 'large'. This Greek root itself descends from the Proto-Indo-European base meǵh₂-, which carried the core meaning of 'great' and is also the ancestor of Latin 'magnus' and Sanskrit 'mahi'. In its journey into English, primarily through scientific vocabulary in the 19th century, it was adopted as a standard prefix in the metric system to denote a factor of one million. Over time, its use expanded beyond technical contexts into general informal language, where it amplifies nouns to mean 'very large' or serves as a standalone term of enthusiastic approval, thus preserving and extending its ancient sense of greatness.

The word 'mega' is a simplex borrowing from Greek. It functions as a combining form or a standalone adjective/adverb in modern English.