ENGLISH
REFERENCE

reactive

adj.
US //ɹiˈæktɪv// UK //ɹɪˈæktɪv// re·ac·tive
  1. 1 responding to events (adj.)
    B2 Upper Intermediate

    acting only after something has happened, rather than planning for it before it happens.

    characterised by a tendency to respond to events after they occur rather than initiating proactive measures.

    Example

    The company was too reactive and only fixed the problem after customers complained.

    Example

    A reactive management style often leads to crisis-driven decision-making, whereas a proactive approach identifies potential risks before they manifest as systemic failures.
  2. 2 chemical change (adj.)
    C1 Advanced Technical Science

    describing a substance that changes easily when it comes into contact with another substance.

    readily taking part in chemical reactions; having a high degree of chemical activity.

    Example

    Potassium is a highly reactive metal that must be stored in oil.

    Example

    The laboratory technician warned that the compound was extremely reactive when exposed to even trace amounts of atmospheric moisture.
Show 1 more senseShow fewer
  1. 3 electrical circuits (adj.)
    C2 Proficiency Technical Science

    related to parts of an electric circuit that store energy instead of just letting it flow through.

    pertaining to a circuit or component characterised by induction or capacitance rather than pure resistance.

    Example

    The engineer measured the reactive power to check the efficiency of the motor.

    Example

    In AC power systems, reactive loads can cause the voltage and current to fall out of phase, necessitating the use of capacitors for power factor correction.
    • resistive
Origin

From react + -ive.

Word family

© 2026 English Reference