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Word of the day

Learn one new word, every day

Every day we features a single English word worth knowing — with its pronunciation, a clear definition, and a real example sentence. Read today's word below, or look up any past day in the archive.

August 27, 2026

catalyst

/ˈkæt.əl.ɪst/noun

A substance that speeds up a chemical reaction while remaining unchanged itself.

Example sentence

  • The enzyme acts as a catalyst, making the reaction happen much faster.

Widely used outside chemistry for any person or event that triggers change: 'a catalyst for reform'.

Archive

239 past words of the day.