plew-
“to flow, to swim”flow, float, swim
Root for flowing/swimming, yielding Latin pluere (to rain), Greek plein (to sail), English flow/float.
Discussion
The Proto-Indo-European root *plew- (to flow, to swim, to fly) is among the most semantically expansive motion roots reconstructable for the proto-language, its descendants spanning the domains of water, air, and rapid terrestrial movement across virtually every IE branch. Pokorny (IEW 835–837) devotes several dense columns to the root and its extensions, reflecting a proliferation of suffixed and graded forms that few other PIE roots can match. The fundamental sense appears to have been fluid, continuous motion, a meaning abstract enough to generate both flow and fly without contradiction. In Germanic, the root produced an astonishing cluster: English flow (from Old English flōwan), float (from Old English flotian), flood (from Old English flōd), fleet (both the adjective meaning swift and the noun for a group of ships), and fly (from Old English flēogan, with an extended *plew-g- form). That a single PIE root underlies words for swimming, sailing, raining, and flying testifies to a conceptual unity of motion-through-medium that modern English has since fractured into separate semantic fields. Latin pluvia (rain) — whence English pluvial — derives from a form meaning that which flows down, with the characteristic Latin treatment of PIE *pl-. Greek pleîn (to sail, to swim) preserves the aquatic sense directly and generated a family of nautical terms. The full grade *plew- appears in Latin pluit (it rains) and the zero grade *plu- in Greek plýnein (to wash). Beekes traces the Greek forms carefully, noting the absence of laryngeal complications that might otherwise obscure the root shape. Watkins highlights *plew- as a case study in how PIE roots could radiate across semantic space when the core motion-concept was sufficiently general. The Old Irish lúaith (swift) and Welsh llif (flood, stream) confirm Celtic participation in the pattern. In the Balto-Slavic branch, Lithuanian plūsti (to float, to drift) and Old Church Slavonic pluti (to swim, to sail) maintain the aquatic core with notable conservatism. The sheer reach of *plew- across English alone — from the poetic (fleet) to the meteorological (flood) to the mundane (flow) — makes it one of the most consequential PIE roots for the history of the English lexicon.
Notes
Pokorny 835-837. LIV *plew-. Germanic *flowan-.
Related Roots
English Words from *plew-
These modern English words descend from this root. Each page traces the full journey from PIE to present-day English.