formidable

adjective

for·​mi·​da·​ble ˈfȯr-mə-də-bəl  fȯr-ˈmi-də-bəl 

fər-ˈmi-də-bəl

1

: causing fear, dread, or apprehension : very difficult to deal with

a formidable challenge

The mountains were a formidable barrier.

2

: having qualities that discourage approach or attack : very powerful or strong

a formidable enemy/opponent/weapon

3

: tending to inspire awe or wonder : impressive

a formidable accomplishment

formidability

ˌfȯr-mə-də-ˈbi-lə-tē 

fȯr-ˌmi-də-ˈbi-lə-tē, 

fər-ˌmi-də-ˈbi-lə-tē

noun

formidableness

ˈfȯr-mə-də-bəl-nəs 

fȯr-ˈmi-də-bəl-nəs, 

fər-ˈmi-də-bəl-nəs

noun

formidably

ˈfȯr-mə-də-blē 

fȯr-ˈmi-də-blē, 

fər-ˈmi-də-blē

adverb

a formidably long list

Synonyms of formidable

• terrifying
• frightening
• scary
• terrible
• horrible
• intimidating

Examples of formidable in a Sentence

She was known throughout Manchester as a formidable woman, and being educated had only piled more formidability on top of what she had been born with. —Edward P. Jones, The Known World, 2003

The technology was formidable: using two and a half million rivets, 300 steeplejacks working flat out would run it up in the space of two years … —Alistair Horne, Seven Ages of Paris, 2002

Alta is reached by a hairpin road that climbs steadily upward—a ride of thirty minutes or so, depending on road and weather conditions—through some of the most formidable mountain scenery in the country. —Cynthia Zarin, New Yorker, 23 Mar. 1992

The mountains were a formidable barrier.

He has mastered a formidable amount of material.

Recent Examples on the Web

The Cuban military, once a formidable expeditionary force during Cold War campaigns in Africa, now struggles with chronic fuel shortages, aging equipment, limited mobility and poor readiness, Pérez said. —Antonio María Delgado, Miami Herald, 28 May 2026

The elder Jackson, one of Chicago’s most famous civil rights icons, died in February and left his formidable organization to his son Yusef. —Alice Yin, Chicago Tribune, 28 May 2026

Baseball is already a long season relative to other professional sports, making for a formidable task in ticket sales. —Sacbee.com, 28 May 2026

Texas Attorney General Ken Paxton has proven to be a formidable candidate — weathering years worth of controversies in his personal and professional life while seeing political success. —Fort Worth Star-Telegram, 27 May 2026

Word History

Etymology

Middle English, from Latin formidabilis, from formidare to fear, from formido terror, bogey; akin to Greek mormō bogey

First Known Use

15th century, in the meaning defined at sense 1

Kids Definition

formidable

adjective

for·​mi·​da·​ble ˈfȯr-məd-ə-bəl 

also

fȯr-ˈmid- 

1

: causing fear or dread

a formidable foe

2

: offering serious difficulties

the mountains were a formidable barrier

3

: very impressive

had won a formidable number of medals

formidableness noun

formidably

-blē 

adverb