English Reference
verb · adjective

diffuse

v. · adj.
US /dɪfˈjus/ dif·fuse UK spelling diffused, diffuses

  1. 01 C1 Advanced Technical Science

    v.to spread out slowly through a liquid, the air, or a large area.

    v.to spread or scatter widely; in physics, the movement of particles from an area of high concentration to low concentration.

    Simple

    The smell of fresh coffee began to diffuse through the entire house.

    In context

    The dye will diffuse through the water until the liquid reaches a uniform shade of blue.

    Usage

    Used both transitively (to diffuse something) and intransitively (something diffuses).

  2. 02 C2 Proficiency FormalAcademic

    adj.using too many words to explain something.

    adj.using more words than necessary; lacking conciseness in speech or writing.

    Simple

    His writing style is quite diffuse, making it hard to find his main point.

    In context

    The professor's diffuse lecture style often led the class far away from the original topic of discussion.

    verbosewordyrambling

Created when light is absorbed, excitons diffuse through the semiconducting material before they can dissociate into free charge carriers to generate electricity.

Phys.org· 19 Aug 2026

The effects of idling reduction laws are hard to estimate, in part because the pollution from idling is diffuse and intermittent.

The Conversation· 31 Jul 2026

Etymology 1

From Middle French diffuser, from Latin diffūsus, past participle of diffundere, from dis- + fundere.

Etymology 2

From Middle English *diffuse (attested in adverb diffuseli), from Latin diffūsus.

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

This entry
Origin Latin diffūsus
Level C1 · Advanced
Frequency Frequent
Updated