hellacious

or hel·la·ceous

[ he-ley-shuh s ]
/ hɛˈleɪ ʃəs /

adjective Slang.

remarkable; astonishing: They're raising a hellacious amount of money in taxes.
formidably difficult: We had a hellacious time getting here in the blizzard.

Origin of hellacious

hell + -acious (extracted from audacious, sagacious, vivacious, etc.), perhaps with intensive or augmentative force; cf. bodacious, splendacious

British Dictionary definitions for hellacious

hellacious
/ (hɛˈleɪʃəs) /

adjective US slang

remarkable; horrifying
wonderful; excellent

Word Origin for hellacious

C20: from hell + -acious as in audacious