English Reference
adjective

spontaneous

adj.
US /spɑnˈteɪniəs/ UK /spɒntˈeɪniəs/ spon·ta·neous

  1. 01 B2 Upper Intermediate

    done or said in a natural way without being planned first.

    arising from a momentary impulse or natural feeling rather than premeditation.

    Simple

    We made a spontaneous decision to go to the beach since the weather was so beautiful.

    In context

    The crowd broke into spontaneous applause as the soloist finished her performance, a reaction that clearly moved the young musician.

  2. 02 C1 Advanced Technical Science

    happening on its own without any outside cause or help.

    occurring without apparent external influence or cause; self-generated.

    Simple

    The forest fire was caused by spontaneous combustion in the dry heat.

    In context

    The chemical reaction was entirely spontaneous, requiring no external heat source to initiate the transformation of the compounds.

    automaticself generated
  3. 03 C2 Proficiency Literary

    growing or produced naturally without people planting or managing it.

    produced without human cultivation, labour, or intentional planting.

    Simple

    The garden was filled with the spontaneous growth of local wildflowers.

    In context

    The valley was noted for its spontaneous vegetation, where rare orchids flourished without any human intervention for centuries.

Usage respectively spontaneous

Kent Police, which made no arrests, described it as a "spontaneous" protest, while Mike Tapp MP said questions need to be asked around why it appeared the police "didn't know about it".

BBC News· 5 Sept 2026

They want to have healthy families, and they have very high standards for what a healthy family is." Going no contact is rarely a spontaneous or easy decision.

Phys.org· 21 Aug 2026

Learned borrowing from Late Latin spontāneus.

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

This entry
Level B2 · Upper Intermediate
Frequency Frequent
Updated