English Reference
adjective

crucial

adj.
US /ˈkɹuʃəɫ/ UK /kɹˈuːʃəl/ cru·cial

  1. 01 B2 Upper Intermediate AcademicGeneral-service

    extremely important because it will affect the final result of something.

    essential or decisive for determining the outcome or future of a situation; vital to success.

    Simple

    The goalkeeper made a crucial save in the final minute of the game.

    In context

    The research team reached a crucial stage in the experiment where any minor error could invalidate months of data collection.

    Usage

    Often followed by the prepositions 'to' or 'for'.

    Pitfall
    This is more crucial than that. This is more important than that.

    While common in speech, 'crucial' is often considered a non-gradable adjective in formal writing; something is either crucial or it is not.

  2. 02 C1 Advanced SlangInformalDialect Music

    very good or excellent, especially when talking about music.

    a slang term of approval meaning excellent or of high quality; historically associated with reggae culture.

    Simple

    That new track they played last night was absolutely crucial.

    In context

    The DJ was known for spinning crucial reggae cuts that you couldn't hear anywhere else in the city.

    Teacher's tip

    This usage is specific to certain dialects and subcultures, particularly in Jamaican English; learners should use 'essential' in most other contexts.

    excellentgreattop tier
  3. 03 C2 Proficiency ArchaicTechnical Science

    shaped like a cross.

    having the form of a cross; cruciform.

    Simple

    The botanist noted the crucial arrangement of the petals on the rare flower.

    In context

    The ancient structure was built upon a crucial ground plan, with four wings extending from a central hub.

    Usage

    In modern English, 'cruciform' is almost always preferred for this meaning.

    cruciformcross shaped

Usage crucial first · crucial aspect · crucial component

It was a great luxury to work that way.” Cultural exchange has always been a crucial part of Japan’s story and how its art travels.

The Guardian· 14 Aug 2026

He also gains the trust of the riverland armies, who play a crucial role in season three.

BreakingNews.ie· 17 Aug 2026

1706, from French crucial, a medical term for ligaments of the knee (which cross each other), from Latin crux, crucis (“cross”) (English crux), from the Proto-Indo-European *(s)ker- (“to turn, to bend”). The meaning “decisive, critical” is extended from a logical term, Instantias Crucis, adopted by Francis Bacon in his influential Novum Organum (1620); the notion is of cross fingerboard signposts at forking roads, thus a requirement to choose.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin ine-pro *(s)ker-
Level B2 · Upper Intermediate
Frequency Common
Updated