For it (actor -um-) to rain something, presumably rain, (theme i-) finely and extensively.
A substantive with actor role occurs only in the sentence unidentified as a pronoun -na `it'; a substantive with theme role is unexpressed in the sentence.
Lumomlom ad ugwan.
(It) is raining finely and extensively now.
Ilomlom: occurs with a pronoun -na, `it' as a non-focused actor:
Un ītang di tinamūanmid ugga ti unna inlomlom at humewol di iddungmi.
We only worked a little bit yesterday because it rained finely and extensively and so our rain baskets we covered ourselves with got in the way.