reactive

/riˈæktɪv/ (bre, ipa) · /riˈæktɪv/ (ame, ipa) · /rē-ˈak-tiv/ (ame, mw)

reactive — adjective

  • reactivepositive
  • more reactivecomparative
  • most reactivesuperlative

1. describing a person, team, or system that deals with problems only after they ha

1.形容詞B2
釋義

describing a person, team, or system that deals with problems only after they happen, rather than taking action beforehand to prevent them.

例句

Talia's team took a reactive approach, fixing bugs only after customers reported them.

reactive approach — common collocation in management writing

Rafael warned the board that a purely reactive strategy would leave them trailing behind competitors.

同義詞
  • passive

    stronger implication of inaction; reactive at least responds, passive may do nothing

  • defensive

    narrower scope — focuses on warding off threats rather than responding to any event

  • responsive

    positive connotation of quick helpful reaction; reactive often carries a negative sense of being too late

反義詞
  • proactive

    acting in advance to prevent or shape events rather than reacting to them

文法句型

reactive + noun

be + reactive

用法筆記

Frequently contrasted with proactive in business and management writing. The subject is typically an approach, strategy, team, or organizational culture — not an individual's personality trait.

常見錯誤

❌We need a proactive team that only fixes problems after they appear.
✅We need a proactive team that prevents problems before they appear.
💡'proactive' means acting in advance; 'reactive' means responding after the fact. Learners often confuse the pair.

2. describing a substance that easily undergoes chemical change when it comes into

2.形容詞B2
釋義

describing a substance that easily undergoes chemical change when it comes into contact with another material.

例句

Rin's chemistry teacher explained that sodium is highly reactive and must be kept under oil.

highly reactive — adverb + adjective intensifier pattern

Saira checked the data sheet to find which reactive compounds were in the mixture.

同義詞
  • unstable

    broader term covering both chemical and physical instability; reactive is specifically about tendency to change chemically

  • volatile

    implies evaporation or explosive risk; reactive covers any chemical change including mild ones

  • active

    vaguer term; reactive is more precise in chemistry contexts

反義詞
  • inert

    describes substances that do not readily undergo chemical change, such as noble gases

  • stable

    describes substances that resist chemical change under normal conditions

文法句型

be + reactive

highly reactive + noun

reactive + noun

用法筆記

Common in laboratory and industrial safety contexts. Elements near the top of the reactivity series (e.g. alkali metals, halogens) are typically described as highly reactive. Often appears in warnings and handling instructions.

常見錯誤

❌Lithium is a reactive reaction.
✅Lithium is a reactive element.
💡'reactive reaction' is redundant; the quality of being reactive already implies a tendency to react.

3. describing a living organism, organ, or tissue that quickly responds to sensory

3.形容詞C1
釋義

describing a living organism, organ, or tissue that quickly responds to sensory input such as touch, light, sound, or chemical contact from its surroundings.

例句

Ayana noticed that her skin was unusually reactive to the ingredients in the new lotion.

reactive to [substance] — preposition pattern for stimuli

The doctor shone a light into Dahlia's eyes and confirmed that both pupils were reactive.

pupils were reactive — fixed medical expression

同義詞
  • responsive

    more general term; reactive in medicine implies an observable physical response to a specific stimulus

  • sensitive

    overlaps in meaning but broader — can include emotional sensitivity; reactive is physical only

反義詞
  • unresponsive

    medical term for tissue or organ that does not respond to stimuli

文法句型

reactive to + noun

用法筆記

Primarily used in medical examinations and biological descriptions. Pupil reactivity and skin reactivity are the most common clinical contexts. Distinguish from sense 2: this sense applies to living tissue responding to stimuli, not to chemical substances reacting with each other.

常見錯誤

❌The patient's skin is reactive to sunlight — it must be stored in a cool place.
✅The patient's skin is reactive to sunlight
💡she must avoid prolonged exposure.' — 'stored' is used for objects and substances (sense 2), not for living tissue (sense 3).