by chance, by accident, at random · without design, intent, or purpose · casually, fortuitously, rashly, heedlessly, thoughtlessly, inconsiderately, indiscreetly, idly
köken: From Proto-Italic *temezi (“in darkness, blindly”), a fossilised locative form of Proto-Indo-European *témHos (“darkness”), from *temH- (“dark”). Cognate with Sanskrit तमस् (támas), Persian تم (tam), Latin tenebrae (“darkness”). Compare this form – here simply adverbial – with the history of the Latin present active infinitive; see -ere.
köken: Most likely a loanword. Its source is unclear; compare Middle Chinese 侹 (MC thengH) "long, level, straight (obsolete)" → SV: thính. See also bằng. The native Vietic word for "straight" is ngay, which also has Khmuic cognates. It is a semantic loan from English straight, in the sense of “heterosexual”.
From Old Galician-Portuguese a eito (13ᵗʰ century, Cantigas de Santa Maria), from a (from Latin ad) + eito (from Latin ictus). Cognate with Portuguese a eito and Spanish a hecho.