\ ˈsē-ˈfȯr How to pronounce C-4 (audio) \

Definition of C-4

 (Entry 1 of 6)

: a high explosive composed of various chemicals that make it moldable and plastic Before it was detonated, I held a piece of C-4 plastic explosive about the size of a baseball. It felt slightly greasy and granular, but otherwise indistinguishable from my daughter's Play-Doh.— Eric Schlosser
\ ˈfȯr-ˈef How to pronounce 4-F (audio) \

Definition of 4-F (Entry 2 of 6)

: classification as unfit for military service also : a person having this classification
\ ˈfȯr-ˈāch How to pronounce 4-H (audio) \

Definition of 4-H (Entry 3 of 6)

: of or relating to a program set up by the U.S. Department of Agriculture originally in rural areas to help young people become productive citizens by instructing them in useful skills (as in agriculture, animal husbandry, and carpentry), community service, and personal development

2,4-D

noun (3)
\ ˌtü-ˌfȯr-ˈdē How to pronounce 2,4-D (audio) \

Definition of 2,4-D (Entry 4 of 6)

: a white crystalline irritant compound C8H6Cl2O3 used especially as a weed killer

2,4,5-T

noun (4)
\ ˌtü-ˌfȯr-ˌfīv-ˈtē How to pronounce 2,4,5-T (audio) \

Definition of 2,4,5-T (Entry 5 of 6)

: an irritant crystalline compound C8H5Cl3O3 used especially formerly chiefly as an herbicide and defoliant

helium-4

noun (5)

Definition of helium-4 (Entry 6 of 6)

Other Words from C-4

Adjective

4-H'er \ ˈfȯr-​ˈā-​chər How to pronounce 4-H'er (audio) \ or less commonly 4-Her noun

First Known Use of C-4

Noun (1)

1964, in the meaning defined above

Noun (2)

1942, in the meaning defined above

Adjective

1926, in the meaning defined above

Noun (3)

circa 1945, in the meaning defined above

Noun (4)

1946, in the meaning defined above

History and Etymology for C-4

Adjective

from the fourfold aim of improving the head, heart, hands, and health

Noun (3)

di-

Noun (4)

tri-

Noun (5)

helium + 4, mass number of the isotope

Keep scrolling for more

Learn More about C-4

Dictionary Entries near C-4

c'mon

C++

c3

C-4

ca

Ca

CA

See More Nearby Entries 

Statistics for C-4

Cite this Entry

“C-4.” The Merriam-Webster.com Dictionary, Merriam-Webster Inc., https://www.merriam-webster.com/dictionary/4. Accessed 28 January 2020.

Keep scrolling for more

More Definitions for C-4

How to pronounce helium-4 (audio)

English Language Learners Definition of 4-H

: of or relating to a government program in the U.S. that teaches farming skills and good citizenship to young people

Comments on C-4

What made you want to look up C-4? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

showing steady, earnest care and effort

Get Word of the Day daily email!

Test Your Vocabulary

Intact Latin Quiz

  • roman tablet
  • What did focus mean in Latin?
Spell It

Can you spell these 10 commonly misspelled words?

TAKE THE QUIZ
Add Diction

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!