profusion (n.) 1540s, "extravagance, expenditure, prodigality, waste," from French profusion (16c.) and directly from Late Latin profusionem (nominative profusio) "a pouring out," noun of action from past-participle stem of profundere "to pour forth" (see profuse). Meaning "abundance, superfluity" is from 1705. effusion (n.) c. 1400, effusioun, "a pouring out," from Old French effusion (14c.) and directly from Latin effusionem (nominative effusio) "a pouring forth," noun of action from past participle stem of effundere "pour forth, spread abroad; to lavish, squander, waste," from assimilated form of ex "out" (see ex-) + fundere "to pour" (from nasalized form of PIE root *gheu- "to pour"). Figuratively, of speech, emotion, etc., from 1650s. suffusion (n.)
late 14c., suffusioun, in pathology, "a cataract; defluxation of a humor," from Latin suffusionem (nominative suffusio) "a pouring over," noun of action from past-participle stem of suffundere "overspread, pour beneath, pour upon," from sub"under" (see sub-) + fundere "to pour" (from nasalized form of PIE root *gheu- "to pour").
It is attested by 1610s as "act or operation of suffusing;" by 1700 as "that which is suffused, a coloring or tint spread over a surface."
—Etymonline
