Sooth comes from Old English sōth ('truth, true'), from Proto-Germanic *sanþaz ('true, real'), from Proto-Indo-European *h1s-ont- ('being, existing, true'), present participle of *h1es- ('to be'). Archaic. The historical chain includes Old English sōth, Proto-Germanic *sanþaz, and Proto-Indo-European *h1es-. Older glosses in the chain include "truth, true", "true, real", "being, existing, true", and "to be", which help explain the semantic range of the modern word. Morphologically, sooth is best read as borrowing, yielding an English noun and adjective shaped by both form history and later usage. In current English it functions as a noun and adjective, with the sense "truth or reality (archaic)". English derivatives include soothly; related forms include soothsayer and forsooth. The result is an English noun and adjective whose etymology preserves the older forms while supporting the word's specialized modern meaning.