Comments:KW 444, Владимирцов 407, SKE 41; Martin 232, АПиПЯЯ 77. The root seems quite reliable, although not devoid of phonetic peculiarities: the Jpn. form seems to points to a diphthong, while the Turkic and Mong. forms would be better derived from a form like *suč`u or *suč`o.