monstrous
mon-strous
adjective
Resembling a monster; extremely large, ugly, or frightening in appearance.
"A monstrous spider crawled up the wall."
adjective
Morally shocking, outrageous, or extremely unfair and unacceptable.
"The decision was a monstrous injustice."
Thesaurus
Synonyms: ugly, grotesque, atrocious, flagitious, evil, grievous, large, big