Pour
Middle English: of unknown origin.
wiktionary
From Middle English pouren(“to pour”), of uncertain origin. Likely to be of Celtic origin, from Celtic base *purr-(“to jerk, throw (water)”), akin to Welsh bwrw(“to cast, strike, rain”), Scottish Gaelic purr(“to push, thrust, urge, drive”), Irish purraim(“I push, I jerk”). Compare also the rare Dutch pouren(“to pour”).
Displaced Middle English schenchen, Middle English schenken(“to pour”) (from Old English sċenċan(“to pour out”), whence dialectal English shink, and Old Norse skenkja, whence dialectal English skink, and akin to Dutch schenken(“to pour; to gift”)), Middle English ȝeoten, Middle English yetten(“to pour”) (from Old English ġēotan(“to pour”) and akin to German gießen(“to pour”)), Middle English birlen(“to pour, serve drink to”) (from Old English byrelian(“to pour, serve drink to”)), Middle English hellen(“to pour, pour out”) (from Old Norse hella(“to pour out, incline”)). Largely displaced English teem, from Middle English temen(“to pour out, empty”) (from Old Norse tœma(“to pour out, empty”))
pour
etymonline
pour (v.)
"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."
