The katakana syllable オ (o). Its equivalent in hiragana is お (o). It is the fifth syllable in the gojūon order; its position is ア行オ段 (a-gyō o-dan, “row a, section o”).

bead tree (Melia azedarach)

window / (regional, dialect, Etchū region) a deep gap in a mountain ridge (so called for the way the wind blows through, like a window)

lie, falsehood