hellacious

adjective

hel·​la·​cious ˌhe-ˈlā-shəs 

1

: exceptionally powerful or violent

2

: remarkably good

3

: extremely difficult

4

: extraordinarily large

hellaciously adverb

Synonyms

• acute
• almighty
• blistering
• deep
• dreadful
• excruciating
• explosive
• exquisite
• fearful
• fearsome
• ferocious
• fierce
• frightful
• furious
• ghastly
• hard
• heavy
• heavy-duty
• intense
• intensive
• keen
• profound
• terrible
• vehement
• vicious
• violent

Examples of hellacious in a Sentence

Traffic is hellacious this time of day.

the hellacious heat was more than we could bear

Recent Examples on the Web

After a solid start, his defensive flaws and diminished reflexes left him open for a hellacious left hook from Rodriguez. —Brian Mazique, Forbes.com, 4 May 2025

Scott’s hellacious run in hip-hop can be credited to his 100-plus Billboard Hot 100 entries and two blockbuster releases, 2018’s Astroworld and 2023’s Utopia, which both secured the top spot on the Billboard 200. —Carl Lamarre, Billboard, 3 Sep. 2019

The canine snarl and hellacious production of Whole Lotta Red has dissipated for something sleeker, more vaporous. —Olivier Lafontant, Pitchfork, 8 Jan. 2025

Caruso isn't the only reason why the Thunder boast such a hellacious defense this year, but he's been a major contributor to it. —Bryan Toporek, Forbes, 24 Dec. 2024

Word History

Etymology

hell + -acious (as in audacious)

First Known Use

1929, in the meaning defined at sense 1

Rhymes for hellacious

• arenaceous
• argillaceous
• carbonaceous
• contumacious
• coriaceous
• efficacious
• farinaceous
• foliaceous
• membranaceous
• ochraceous
• olivaceous
• ostentatious