English Reference
adjective · noun

unpredictable

adj. · n.
US /ˌənpɹɪˈdɪktəbəɫ/ UK /ʌnpɹɪdˈɪktəbəl/ un·pre·dictable

  1. 01 B2 Upper Intermediate

    adj.describing something that changes so much you cannot guess what will happen next.

    adj.not able to be foreseen or known beforehand; lacking a predictable pattern or consistency.

    Simple

    The weather in the mountains is unpredictable, so you should bring a rain jacket.

    In context

    The stock market remained highly unpredictable throughout the fiscal year, defying the projections of even the most seasoned financial analysts.

  2. 02 B2 Upper Intermediate

    adj.describing a person who often changes their mood or actions without warning.

    adj.behaving in a way that is not easily anticipated; often used to describe temperament or personality.

    Simple

    He is a talented actor, but his unpredictable temper makes him difficult to work with.

    In context

    The director found the lead actor's unpredictable outbursts exhausting, as they frequently disrupted the filming schedule and lowered the crew's morale.

  3. 03 C1 Advanced Formal

    n.a person or thing that you cannot predict.

    n.a person, thing, or event that is impossible to predict. Often used in the plural to describe general uncertainties.

    Simple

    In politics, you must always be prepared for the unpredictable.

    In context

    The strategist argued that the success of the campaign depended on how well the team managed the various unpredictables of the local election cycle.

This is "leading to last-minute cancellations [and] unpredictable utilisation of donated organs," he warned.

BBC News· 13 Aug 2026

Hot weather can make travel unpredictable, and access issues can waste valuable time on an already exhausting day.

BBC News· 11 Aug 2026

From un- + predictable.

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

This entry
Level B2 · Upper Intermediate
Frequency Frequent
Updated