Capricious vs Mercurial: What’s the Difference?

The difference at a glance

Both describe unpredictable changeability, but from different angles. Capricious suggests changes governed by whim or impulse — the mood shifts without apparent reason. Mercurial implies rapid changes of feeling with a quicksilver quality — more temperature-based than purely random. The capricious person acts on whim; the mercurial one shifts mood like weather. Mercurial often carries a hint of brilliance; capricious suggests unreliability.

What does Capricious mean?

adjective · /kəˈprɪʃəs/

Changing mood or behaviour suddenly and unexpectedly; governed by impulse rather than reason.

Capricious in a sentence

The committee's capricious decisions made long-term planning nearly impossible.

She was capricious in her affections — devoted one moment, indifferent the next.

What does Mercurial mean?

adjective · /mɜːˈkjʊəriəl/

Subject to sudden, unpredictable changes of mood or mind; quick-witted, lively, and volatile in a way that is both unsettling and magnetic. Impossible to fully anticipate.

Mercurial in a sentence

His mercurial temperament kept everyone around him slightly off-balance.

She was mercurial — furious at noon, laughing by afternoon, impossible to predict and hard to leave.

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