From Proto-Mongolic *nïlbusun, likely related or influenced by other *nï- words, see нус (nus, “snot”).
Compare Buryat нёлбоһо (njolboho), Mongghul ninpuzi, Dongxiang nubusun.
нулимс • (nulims) (Mongolian spelling ᠨᠢᠯᠪᠤᠰᠤ (nilbusu)); (hidden-n declension )