The story
- Proto-Indo-European*né
- Proto-Indo-European*n̥-
- Proto-Germanic*un-
- Proto-West Germanic*un-
- Old Englishun-
- Middle Englishun-
- Englishun-
- Proto-Indo-European*h₂éd
- Proto-Italic*ad
- Proto-Italic*ad-
- Latinad-
- Proto-Indo-European*gʰredʰ-
- Latingradior
- Latinaggredior
- Latinaggressu
- Englishaggress
- Englishaggressive
- Englishunaggressive
- Proto-Indo-European*leyg-
- Proto-Germanic*līką
- English todayunaggressively
From unaggressive + -ly.
Etymology from Wiktionary, CC BY-SA 4.0.