spontaneous

spontaneous — adjective

1. done because you feel like doing it at that moment, not because you had planned

1.形容詞B2
釋義

done because you feel like doing it at that moment, not because you had planned or thought about it beforehand — for example, a spontaneous round of applause, a spontaneous decision to take a trip, or a spontaneous gesture of thanks.

例句

Jude gave his grandmother a spontaneous hug the moment she arrived at the door.

spontaneous + [action noun] describing an unplanned gesture

The audience burst into spontaneous applause as the young cellist finished her piece.

collocation: spontaneous applause / spontaneous decision

同義詞
  • unplanned

    more neutral and factual; lacks the positive energy of 'spontaneous'

  • impulsive

    suggests acting without thinking, often with a slightly negative or risky tone

  • natural

    focuses on relaxed, unforced quality rather than the suddenness

  • unscripted

    limited to performances, speeches, or media content that is not read from a prepared text

反義詞
  • planned

    arranged or decided beforehand

  • rehearsed

    practised in advance, especially for a performance

  • deliberate

    done consciously and intentionally, often after careful thought

文法句型

a spontaneous + [action noun]

be + spontaneous

seem/appear/feel + spontaneous

用法筆記

This sense is gradable — an action can be very spontaneous or completely spontaneous, depending on how much it was driven by sudden feeling versus any trace of planning. Frequently used to describe positive, warm, or lively behaviour.

常見錯誤

❌The meeting was spontaneous because we scheduled it for 3 p.m.
✅The meeting was scheduled, not spontaneous.
💡Something that is planned cannot also be spontaneous.
❌He made a spontaneous purchase without thinking about the cost.' (preferred: impulsive)
✅He made a spontaneous decision to join his friends for lunch.
💡'Spontaneous' emphasises natural, unforced choice; 'impulsive' adds the idea of acting without enough thought, often with a slightly negative tone.

2. happening within an organism or natural system because of changes inside itself

2.形容詞C1
釋義

happening within an organism or natural system because of changes inside itself — such as chemical reactions, cell changes, or biological processes — rather than from a cause or trigger outside it.

例句

The doctor explained that the bleeding was spontaneous and not caused by any injury.

medical usage: spontaneous bleeding / spontaneous recovery

Spontaneous combustion can occur when a pile of oily rags heats up on its own.

technical term: spontaneous combustion

同義詞
  • automatic

    describes a process that happens by itself as part of a system, often mechanical or physiological

  • involuntary

    focuses on lack of conscious control, used for body functions like breathing or blinking

  • self-generated

    emphasises that the cause comes from within rather than from outside

  • innate

    suggests something present from birth rather than developing later by itself

反義詞
  • induced

    brought about intentionally by an external agent, e.g. induced labour

  • triggered

    caused by a specific outside event or stimulus

  • artificial

    produced by human intervention rather than natural processes

文法句型

spontaneous + [medical / scientific noun]

用法筆記

Primarily appears in medical and scientific writing. Unlike sense 1, this sense is rarely used with intensifiers such as 'very' (we do not say 'very spontaneous combustion'). Common pairings include spontaneous combustion, spontaneous remission, spontaneous recovery, spontaneous mutation, and spontaneous bleeding.

常見錯誤

❌The trash fire was spontaneous.
✅The trash fire was caused by spontaneous combustion of damp hay.
💡Without specifying the internal chemical process, the meaning is unclear; 'spontaneous' in this sense needs a scientific context.
❌She had a very spontaneous recovery from the flu.
✅She had a surprisingly quick recovery from the flu.
💡'Spontaneous recovery' is a medical term for recovery without treatment, not a synonym for 'fast recovery'.