The word is commonly assumed to derive from Mongolic, see Mongolian сувай (suvaj, “sterile, barren”). Cognate with Kyrgyz субай (subay, “barren animal”), Yakut субай (subay, “barren animal; animals to be slaughtered”); Chagatai [script needed] (subay, “unladen; single; light cavalry”). The sense 'bachelor; childless' occurs in Turkish dialects as well, possibly as a borrowing from Azerbaijani. According to Doerfer, the word underwent the following semantic developments in (primarily) Central Asian Turkic languages: 'barren'→ 'unattached, not married' → 'light cavalry (unattached, unburdened by load)'; he then attributes Turkish subay (“officer”) to a semantic narrowing of an unattested sense '*light cavalry officer'. However, neither Azerbaijani nor Ottoman Turkish have the sense 'officer'. Alternatively, the Turkish subay (“officer”) was coined as a replacement for Ottoman Turkish ضابط (“zâbit”) during the Turkish language reform, in which case the coinage was a misinterpretation of Chagatai [script needed] (subay) as a compound cognate with Old Turkic 𐰾𐰇 (s²ü, “army; spearmen; heavily armed pedestrian or horsemen”) and Old Turkic 𐰋𐰏 (b²g, “lord”).