adj. 25B6; adjective
a grin of unholy amusement : UNGODLY, godless, irreligious, impious, blasphemous, sacrilegious, profane, irreverent; wicked, evil, immoral, corrupt, depraved, sinful.
(informal) an unholy row : SHOCKING, dreadful, outrageous, appalling, terrible, horrendous, frightful.
an unholy alliance : UNNATURAL, unusual, improbable, made in Hell.