Where does “rainfast” come from?

rainfast (English) comes from English fast, from Middle English fast, from Old English fæste, from Old English -e, from Old English -en, from Old Norse -inn, from Proto-Norse -īna-, from Proto-Germanic -īnaz — adjectival suffix.

rainfast (English): That is not washed off by the rain

Definitions

  1. That is not washed off by the rain

Ancestry of “rainfast”, step by step

rainfast traces back through two separate lines of ancestry.

via English fast

StepLanguageWordMeaning
1EnglishfastFirmly or securely fixed in place; stable; Firm...
2Middle Englishfastfast quickly
3Old Englishfæstefirmly, fastly, tightly
4Old English-eforming adverbs from adjectives; -ly
5Old English-enmæġþ + API → mæġden; cocc + API → cycen, cicen;...
6Old Norse-innUsed to create adjectives from nouns, meaning...
7Proto-Norse-īna-
8Proto-Germanic-īnaz-en
9Proto-Indo-European-iHnosCreates adjectives of materials
10Proto-Indo-European-no-adjectival suffix

via English rain

StepLanguageWordMeaning
1EnglishrainCondensed water falling from a cloud; Any matter...
2Middle Englishreynrain water falling from a cloud
3Old Englishreġnrain
4Proto-West Germanicregnrain
5Proto-Germanicregnąrain
6Proto-Indo-EuropeanHreǵ-to flow
Every word from Proto-Indo-European -no-