The story
- Proto-Indo-European*h₁én
- Proto-Italic*en
- Proto-Italic*en-
- Latinin-
- Proto-Indo-European*bʰer-
- Proto-Indo-European*bʰéreti
- Proto-Italic*ferō
- Latinferō
- Latinīnferō
- Latinīnfrā
- English todayinfra-
Borrowed from Latin īnfrā (“below”).
Etymology from Wiktionary, CC BY-SA 4.0.