Etymon
gem-hrewwana-protowest-germanic-hreuwan-protoindoeuropean-h2-protoindoeuropean-eh2-protogermanic-o-protowest-germanic-u-protowest-germanic-hreuwu-old-english-hreow-middle-english-rewe-protoindoeuropean-pleh1-protoindoeuropean-nos-protoindoeuropean-plh1nos-protogermanic-fullaz-protogermanic-fullaz-old-english-ful-middle-english-ful-middle-english-reuful-english-rueful-protogermanic-in-protoindoeuropean-h2-protoindoeuropean-eh2-protoindoeuropean-yeti-protoindoeuropean-eh2yeti-protoindoeuropean-h2ti-protogermanic-ona-protogermanic-inona-protoindoeuropean-dye-protogermanic-atjana-protoindoeuropean-tus-protogermanic-uz-protogermanic-assuz-protogermanic-inassuz-protowest-germanic-nassi-old-english-nes-middle-english-nesse-english-ness-english-ruefulness-from-rueful-ness
A dedicated page for this root is on the way — it will gather every word descended from it, sibling forms across daughter languages, and a branching map of the family tree.