rewk-
“to be bright, light”light, bright, luminous
Root for brightness, yielding English light-related words, possibly related to *lewk-.
Discussion
The root *rewk- has been reconstructed with the meaning "to be bright" or "to shine," though its boundaries remain contested. The difficulty centers on its relationship to the far better-attested *lewk- ("light, brightness"), source of Latin lūx and the vast lucid/elucidate/lunar family. Some scholars treat *rewk- as a dialectal variant or metathesized form of *lewk-; others maintain it as independent. Pokorny (874) listed the root with connections to brightness, though subsequent scholarship has refined these assignments. Rix does not include *rewk- as a separate entry in LIV², suggesting its verbal reflexes may have been absorbed into the *lewk- family. What is clear is that the PIE vocabulary of light was rich and differentiated, likely including multiple roots that overlapped semantically while maintaining formal distinction. Whether *rewk- represents an independent root or a variant of *lewk- remains open.
Notes
Pokorny 869. Compare *lewk- for primary light root.