Comments:JLTT 448. Historically a compound with *pur- 'to wave' (or *pur- 'to snow, rain'); the Ryukyu variant *kaiNpusi may reflect a different suffixation (or the influence of *mus- 'to boil, steam'). Simple *kai is also attested in OJ as ke 'vapour, breath'; the word is traditionally regarded as borrowed < MChin. khɨ̀j id., but the vocalism is somewhat strange (one would rather expect OJ ki - which, as a matter of fact, is also attested and is the normal Goon / Kanon reading of the character 氣).