出典:Wiktionary
From Middle English watered, watred, ywaterd, y-wattered, i-watred, i-watered, from 古期英語 *wæterod, *ġewæterod, equivalent to water + -ed. Cognate with West Frisian wetterd, Dutch verwaterd, German bewässert.
「watered」は動詞「water」の過去形、または過去分詞です