bʰleg-
“to shine, burn, flash”Source of Latin flagrāre, English flame, flagrant, black
Root for shining and burning, yielding Latin flagrāre (to blaze) and English flame, flagrant.
Discussion
The Proto-Indo-European root *bʰleg- meant "to shine, to burn, to flash" and is notable for having produced descendants with seemingly contradictory meanings — both black and bleach derive from it, reflecting different aspects of fire and its effects. The root captures the visual intensity of flame: its brightness, its capacity to scorch and blacken, and the bleaching effect of strong light.
In the Germanic branch, the root underwent Grimm's Law transformations. The Proto-Indo-European aspirated voiced stop *bʰ became *b in Germanic, yielding Old English blæc "black". The connection between burning and blackness is straightforward: what fire consumes becomes charred and dark. Yet the same root also produced Old English blæce "bleaching, whitening" (modern English bleach), reflecting the opposite effect — the blanching power of sunlight or lye. This semantic split is a celebrated example of how a single root can develop antonymous meanings through different metaphorical extensions. The related word blank, borrowed from Old French blanc, ultimately traces back to the same source through a Germanic intermediary.
Latin inherited the root as flagrare "to blaze, to burn", which gave English flagrant (originally "blazing", now "glaringly offensive"), conflagration, and the word flame itself came through a related Latin form flamma. The Latin word fulgor "lightning flash" and fulgere "to flash" are also connected to this root complex, producing English refulgent.
Greek phlegein "to burn" is a direct cognate, visible in the medical term phlegmon and the mythological river Phlegethon, the river of fire in the underworld. The Greek word also gave rise to phlegmatic, originally referring to the humour associated with excessive moisture — a semantic development that moved far from the root's fiery origins.
The coexistence of black and bleach from a single root remains one of the most instructive examples in Indo-European etymology of how physical processes — in this case, the dual nature of fire as both darkener and brightener — can drive semantic divergence.
Related Roots
English Words from *bʰleg-
These modern English words descend from this root. Each page traces the full journey from PIE to present-day English.