"to cause (liquid or granular substance) to flow or stream either out of a vessel or into one," c. 1300, of unknown origin. Not in Old English; perhaps from Old French (Flanders dialect) purer "to sift (grain), pour out (water)," from Latin purare "to purify," from purus "pure" (see pure). Replaced Old English geotan. Intransitive sense of "to flow, issue forth in a stream" is from 1530s. Related: Poured; pouring; pourable. As a noun from 1790, "a pouring stream."

"raining heavily," c. 1600, present-participle adjective from pour (v.).

mid-15c., "a pouring out, outflow, effusion," from out- + infinitive of pour (v.). From 1757 as "action of pouring out," probably a re-coinage, originally transferred, of things spiritual; sense of "that which is poured out" (again, usually transferred) is from 1827. A verb, outpour "to pour forth," is attested from 1670s.

early 15c., "to pour in, introduce, soak (something in liquid)," from Latin infusus, past participle of infundere "to pour into, pour out; press in, crowd in; mix, mingle," from in- "in" (from PIE root *en "in") + fundere "to pour, melt" (from nasalized form of PIE root *gheu- "to pour"). Related: Infused; infusing; infusory; infusorial.

early 15c., perfusen, "to wash away;" 1520s, "to sprinkle, pour or spread over or through," from Latin perfusus, past participle of perfundere "to pour over, besprinkle," from per (see per) + fundere "to pour, melt" (from nasalized form of PIE root *gheu- "to pour").

also re-pour, c. 1600, "pour back," from re- "back, again" + pour (v.). Related: Repoured; repouring.

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.

"to pour out, spill," late 14c., from French effuser or directly from Latin effusus "poured out," past participle 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"). Related: Effused; effusing. Not to be confused with eff youse.

"to overspread," as with a fluid or tincture; "fill or cover," as with something fluid; 1580s, from Latin suffusus, past participle of suffundere "overspread, pour beneath, pour upon," from sub "under" (see sub-) + fundere "to pour" (from nasalized form of PIE root *gheu- "to pour"). Chauliac (early 15c.) in a now obsolete medical sense has suffunden. Related: Suffused; suffusing.

"milky fluid formed during the process of digestion," 1540s, from Late Latin chylus "the extracted juice of a plant," from Greek khylos "juice" (of plants, animals, etc.), from stem of khein "to pour, gush forth," from PIE *ghus-mo-, from root *gheu- "to pour, pour a libation." Compare also chyme.