thin

The story

1. Proto-West Germanic*þunnī
2. Old Englishþynne
3. Middle Englishthinne /thenne /thünne
4. English todaythin

From Middle English thinne, thenne, thünne, from Old English þynne, from Proto-West Germanic *þunnī, from Proto-Germanic *þunnuz (“thin”) – compare *þanjaną (“to stretch, spread out”) – from Proto-Indo-European *ténh₂us (“thin”), from *ten- (“to stretch”). Cognates Cognate with German dünn, Dutch dun, West Frisian tin, Icelandic þunnur, Danish tynd, Swedish tunn, Latin tenuis, Irish tanaí, Welsh tenau, Latvian tievs, Polish cienki, Russian тонкий (tonkij), Sanskrit तनु (tanú, “thin”), Persian تنگ (tang, “narrow”). Doublet of tenuis. Also related to tenuous.