köken: From Proto-Turkic *ked (“back, after”). Cognate with Southern Altai кийин (kiyin), Karakalpak keyin, Kyrgyz кийин (kiyin), Uzbek keyin, Uyghur كېيىن (këyin), Khakas кизін (kizìn, “back”), etc.
köken: From Proto-Mon-Khmer *krawʔ. Cognate with Muong khau, Mon တြဴ. Attested in Phật thuyết đại báo phụ mẫu ân trọng kinh (佛說大報父母恩重經) as 牢 (MC law) (modern SV: lao) and 娄, alternative form 婁 (MC luw) (modern SV: lâu).
köken: Univerbation of до (do, “until”) + виждане (viždane, “seeing”). Cognate with Russian до свида́ния (do svidánija). Compare parallel and more distant cognate French au revoir, Italian arrivederci, related to Latin videō (+ Latin ad- + Latin re-). Also compare Portuguese até mais ver, Spanish hasta la vista, also related to Latin videō (and probably also + Latin ad).