bʰrewh₁-
“to brew, to boil”brew, boil
Root for brewing and boiling liquids. Gives English "brew", "broth", "bread" (fermented dough).
Discussion
The root *bʰrewh₁- ("to brew, to boil, to bubble") is reconstructed in LIV² (s.v. *bʰrewh₁-) and Pokorny (IEW 143–145). The laryngeal *h₁ is established by the lengthened-grade reflexes and the absence of vowel colouring.
In Germanic, the root is most famously preserved in Old English brēowan ("to brew"), whence Modern English brew. Old High German briuwan, Old Norse brugga, and Middle Dutch brouwen are cognates. The noun broth (Old English broþ) derives from the zero grade *bʰruh₁-to-, meaning "that which has been boiled." Bread may ultimately derive from a related form *bʰrewh₁-d-, though alternative etymologies connecting it to "fragment, morsel" also exist. The cultural significance of brewing in Germanic societies is reflected in the root's productivity.
Latin fervēre ("to boil, to seethe") reflects *bʰrewh₁- with regular *bʰ > f and a somewhat irregular vocalism that has generated scholarly discussion. From fervēre come English fervent, fervid, fervor, and effervesce. The noun fermēntum ("yeast, leaven") gives English ferment and fermentation—the biochemical process originally observed in brewing.
Greek phréar (φρέαρ, "well, spring")—a natural source of bubbling water—may be related, though the phonological details are debated. Thracian brûtos ("a fermented drink") is a further possible cognate.
The semantic core is consistently thermal agitation of liquids: boiling, bubbling, brewing. The extension from boiling to fermentation to bread-making traces a coherent line of culinary technology that was evidently part of the PIE cultural repertoire. The preservation of the root primarily in Germanic and Italic, with sparser reflexes elsewhere, is notable.
Notes
Germanic *breuwan; Latin dēfrūtum (boiled-down must)