adjective noun

1. purified MN.i.386; Snp.351, Snp.786, Snp.813, Snp.834 (= dhutakilesa Snp-a.542); Ja.iii.160 (˚sākha = patthaṭasākha Com.; variant reading BB vena˚); Mnd.77 = Mnd.176 (: dhonā vuccati paññā etc., dhuta & dhota used indiscriminately in exegesis following).
2. (pl. the four requisites of a bhikkhu Dhp-a.iii.344 (: dhonā vuccati cattāro paccayā, in Com. on atidhonacārin Dhp.240; gloss K. dhovanā, cp. Morris, J.P.T.S. 1887 100).

either = dhota, Sk. dhauta, see dhovati or = dhuta, see dhuta & dhunana. Quite a diff. suggestion as regards etym. is given by Kern,

Toevoegselen

117 who considers it as a possible derⁿ fr. adho, after analogy of poṇa. Very doubtful