Synonyms of formidable

formidable

adjective

ˈfȯr-mə-də-bəl 

1

as in terrifying

causing fear

a formidable, irascible old man who frightened the neighborhood children

Synonyms & Similar Words

• terrifying
• frightening
• scary
• terrible
• horrible
• intimidating
• alarming
• dread
• fearful
• fearsome
• redoubtable
• shocking
• startling
• horrifying
• dreadful
• frightful
• eerie
• creepy
• ghastly
• dire
• forbidding
• horrendous
• direful
• gruesome
• threatening
• daunting
• troubling
• trying
• spine-chilling
• disturbing
• hair-raising
• unnerving
• discouraging
• perturbing
• hideous
• disconcerting
• disquieting
• demoralizing
• weird
• dismaying
• monstrous
• distressing
• nightmarish
• grisly
• appalling
• awful
• macabre
• horrid
• bone-chilling
• atrocious

Antonyms & Near Antonyms

• reassuring
• soothing
• comforting
• relaxing
• calming
• inviting
• tranquilizing
• consoling
• nonthreatening
• quieting
• lulling
• pacifying
• nonintimidating

2

as in difficult

requiring considerable physical or mental effort

running a marathon is a formidable undertaking

Synonyms & Similar Words

• difficult
• challenging
• tough
• rigorous
• hard
• demanding
• heavy
• complicated
• rugged
• herculean
• rough
• tall
• severe
• arduous
• strenuous
• murderous
• effortful
• sweaty
• killer
• laborious
• intricate
• complex
• exacting
• grueling
• exhausting
• uphill
• painful
• stiff
• testing
• serious
• backbreaking
• toilsome
• problematic
• elusive
• hellacious
• annoying
• stubborn
• grim
• tricky
• brutal
• thorny
• pick-and-shovel
• oppressive
• troublesome
• bruising
• Augean
• involved
• onerous
• tight
• insoluble
• stressful
• moiling
• hairy
• recondite
• abstract
• abstruse
• irksome
• burdensome
• knotty
• opaque
• ticklish
• spiny
• vexatious
• strict
• bothersome
• labored
• stringent
• cruel
• trying
• grievous
• taxing
• distressing
• inhuman

Antonyms & Near Antonyms

• easy
• simple
• soft
• light
• cheap
• effortless
• clear
• manageable
• facile
• uncomplicated
• undemanding
• achievable
• mindless
• elementary
• doable
• gentle
• smooth
• friendly
• soothing
• comforting
• relaxed
• accessible
• painless
• user-friendly
• idiotproof

Example Sentences

Recent Examples of formidable

Still, researchers like Bobrick, Martire, and others continue exploring the concept and working to better understand both the formidable challenges involved and what the laws of physics may ultimately allow. — Micah Hanks, Space.com, 23 Sep. 2026

Still, many critics expect Digger will be a formidable awards contender, particularly for Cruise’s performance and the film’s production design. — James Hibberd, HollywoodReporter, 23 Sep. 2026

And to do this in a city that plays host to one of the most formidable film cultures in the world! — Liz Shackleton, Deadline, 23 Sep. 2026

Bajo Chiquito sits on the Tuquesa River at the northern end of the Darién Gap, the more than sixty-mile stretch of formidable terrain and riverine forest straddling Panama and Colombia. — Belén Fernández, Harpers Magazine, 22 Sep. 2026