unholy
adj.adj. describing something very bad, unnatural, or shocking. It is also used to describe a combination of things that do not belong together and might cause trouble.
adj. wicked, immoral, or contrary to religious principles; in secular contexts, describes an unnatural or harmful combination of elements. Often used for hyperbolic emphasis to describe something unpleasant or excessive.
The two rivals formed an unholy alliance to win.
The factory began making an unholy noise that could be heard three blocks away.
The merger was described as an unholy alliance between a predatory hedge fund and a struggling public utility, sparking immediate protests from consumer advocacy groups.
From Middle English unholi, unhaliȝ, from Old English unhāliġ, from Proto-Germanic *unhailagaz, equivalent to un- + holy. Cognate with Scots unhaly, Dutch onheilig, German Low German unhillig, German unheilig, Danish uhellig, Swedish ohelig.
Typically used attributively before the noun it modifies.