The adjectives drubly and drumly occur in Scots from the earliest records onwards.
Thik drumly skuggis dyrknyt so the hevyn, Dym skyis oft furth warpit feirfull levyn, Haggis of fire, and mony felloun flaw, Scharpe soppys of sleit and of the snypand snaw.
The etymology of drubly or drumly has been as clouded, muddied, or turbid as its sense.