involving an extremely important decision or result; decisive; critical: a crucial experiment.
severe; trying.
of the form of a cross; cross-shaped.

Origin of crucial

1700–10; < Latin cruci- (stem of crux) cross + -al1
Related formscru·ci·al·i·ty [kroo-shee-al-i-tee, kroo-shal-] /ˌkru ʃiˈæl ɪ ti, kruˈʃæl-/, nouncru·cial·ly, adverbnon·cru·cial, adjectivenon·cru·cial·ly, adverbpre·cru·cial, adjective

Synonyms for crucial Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for crucial

Contemporary Examples of crucial

Historical Examples of crucial

  • Orley slapped his card down; it was a crucial card, the jack.

    Goodbye, Dead Man!

    Tom W. Harris

  • But at any rate, no one will deny that interest is the crucial matter.

  • What names will afford the most crucial test of natural fitness?

  • Mrs. Winthrop helped him by her entrance at this crucial point.

    David Dunne

    Belle Kanaris Maniates

  • The following and last experiment that I tried on this occasion was the most crucial.


    W. W. Baggally

British Dictionary definitions for crucial



involving a final or supremely important decision or event; decisive; critical
informal very important
slang very good
Derived Formscrucially, adverb

Word Origin for crucial

C18: from French, from Latin crux cross
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for crucial

1706, "cross-shaped," from French crucial, a medical term for ligaments of the knee (which cross each other), from Latin crux (genitive crucis) "cross" (see cross (n.)). The meaning "decisive, critical" (1830) is extended from a logical term, Instantias Crucis, adopted by Francis Bacon (1620); the notion is of cross fingerboard signposts at forking roads, thus a requirement to choose.

Online Etymology Dictionary, © 2010 Douglas Harper