The story
- Proto-Germanic*hrewwaną
- Proto-West Germanic*hreuwan
- Proto-West Germanic*hreuwu
- Old Englishhrēow
- Middle Englishrewe
- Old Norsehrygðinflu.
- Middle Englishreuþe
- Proto-Indo-European*pleh₁-
- Proto-Indo-European*pl̥h₁nós
- Proto-Germanic*fullaz
- Middle Englishreuþful
- English todayruthful
From Middle English reuþful, reuthful, reowthful, equivalent to ruth + -ful.
Etymology from Wiktionary, CC BY-SA 4.0.