dif·fuse • v. / diˈfyoōz/ spread or cause to spread over a wide area or among a large number of people: [intr.] technologies diffuse rapidly | [tr.] the problem is how to diffuse power without creating anarchy. ∎  become or cause (a fluid, gas, individual atom, etc.) to become intermingled with a substance by movement, typically in a specified direction or at specified speed: [intr.] oxygen molecules diffuse across the membrane | [tr.] gas is diffused into the bladder. ∎  [tr.] cause (light) to glow faintly by dispersing it in many directions.• adj. / diˈfyoōs/ spread out over a large area; not concentrated: the diffuse community centered on the church the light is more diffuse. ∎  (of disease) not localized in the body: diffuse hyperplasia. ∎  lacking clarity or conciseness: the second argument is more diffuse.DERIVATIVES: dif·fuse·ly / -ˈfyoōslē/ adv.dif·fuse·ness / -ˈfyoōsnis/ n.

diffuse †confused, indistinct XV; opp. of confined and condensed XVIII. — F. diffus (fem. -use) or L. diffūsus extensive, ample, prolix, pp. of diffundere pour out, f. DIF- + fundere pour.
So diffuse vb. XVI. f. diffūs-, pp. stem of L. diffundere. diffusion †outpouring XIV; spreading abroad XVI; permeation of a fluid by another XVIII. — L.