Diffuse
late Middle English: from Latin diffus- ‘poured out’, from the verb diffundere, from dis- ‘away’ + fundere ‘pour’; the adjective via French diffus or Latin diffusus ‘extensive’, from diffundere .
wiktionary
From Middle French diffuser, from Latin diffūsus, past participle of diffundere, from dis- + fundere
From Middle English *diffuse (attested in adverb diffuseli), from Latin diffūsus.
etymonline
diffuse (v.)
1520s (transitive), "to pour out and spread, cause to flow and spread;" 1650s (intransitive), "spread abroad, scatter in all directions;" from Latin diffusus, past participle of diffundere "to pour out or away," from dis- "apart, in every direction" (see dis-) + fundere "to pour" (from nasalized form of PIE root *gheu- "to pour"). Related: Diffused; diffusing.
diffuse (adj.)
early 15c., "hard to understand;" also, of writers, "verbose, using many words;" from Latin diffusus, past participle of diffundere "scatter, pour out," from dis- "apart, in every direction" (see dis-) + fundere "to pour" (from nasalized form of PIE root *gheu- "to pour"). Meaning "widely spread or diffused, scattered" is from late 15c.
