Reconstruction:Proto-Slavic/pyrь

Most likely a substantive i-stem derivative from the direct-case stem of Proto-Indo-European *péh₂wr̥ (“bonfire”), cognate with Old Prussian panno (“fire”) (derived from the oblique-case stem). Further origin is disputed. Commonly proposed etymologies include:

• From *paw- (“to strike”), whence Proto-Slavic *pyti (“to discern”), *pytati (“to examine, to request clarification”).
• From *puH- (“to rot”), whence Lithuanian pū́ti (“to rotten”), Latvian pũt (“to rotten”).
• From *pewH- (“to cleanse, to purify”), whence Latin pūrus (“pure”), pius (“devout”).

All of these roots may ultimately be w-extensions of Proto-Indo-European *(s)peh₂- (“to lash, to thrash, to wrench”) (reflected by Ancient Greek σπᾰ́ω (spắō, “to draw, to pluck”), etc.). Perhaps, from there is semi-onomatopoeic Proto-Slavic *patъ (“thump, smack”), *patati (“to bang”).

*py̑rь m^[1]

1. remains of fire, smoldering ash, cinder

   Synonyms: *sędra, *žarъ

2. (by extension) lye, product of combustion

   Synonyms: *zola, *cědъ

• *pyriti (“to combust, to melt, to fan a fire”)
• >? *pyrovati (“to ferment”)
• *pyrьjь (substantivized noun)
  • → East Slavic:
    • Russian: пы́рей (pýrej, “part of furnace”) (dialectal)
    • Ukrainian: пире́й (pyréj, “cinder”)

• *pylъ m, *pylь f (“dust, cinder”)

• East Slavic:
  • Russian: пуры́нь (purýnʹ), пурина (purina, “ash”) (dialectal)
• South Slavic:
  • Old Bulgarian: пыро (pyro, “spelt”)
  • >? Bulgarian: фир (fir), фур (fur, “acrid, bitter substance”) (dated, in modern times: slang for “booze”)
    • ⇒ пирива́ (pirivá, “acid soil”) (dialectal)
  • Slovene: pír (“smoldering fire”) (tonal orthography) (dialectal), pírh (“coloured Easter egg”), píra (“spelt”)
  • >? Serbo-Croatian: пурњати, [Term?] (“fuming, to smoke”)
• West Slavic:
  • Czech: pýř (“lye”)
  • Old Polish: pyrz (“dust”)
    • Polish: perz (“smoke”)

• Vasmer, Max (1964–1973) “пуры́нь”, in Oleg Trubachyov, transl., Этимологический словарь русского языка [Etymological Dictionary of the Russian Language] (in Russian), Moscow: Progress
• Vasmer, Max (1964–1973) “пы́рей”, in Oleg Trubachyov, transl., Этимологический словарь русского языка [Etymological Dictionary of the Russian Language] (in Russian), Moscow: Progress

Per Trubačev, probably resultant from an alternative semantic development of Etymology 1 stemming back from Proto-Indo-European times. As a reason, he gives the circumstance that spelt needed to be treated thermally in order to be used. Similar semantic duality is observed in Old English fȳr (“fire”) and fyrs (“furze”). For further details, see the o-stem variant *pyrъ.

Possibly akin (via ter-stem) to Proto-Balto-Slavic *putrāˀ (“ground corn, cereal”) (whence Latvian putra (“porridge”)) from one of the above mentioned roots.

*pỳrь m

1. alternative form of *pyrъ: couch grass

• *pyrьjь (“id.”)

• West Slavic:
  • Czech: pýř (“couch grass”) (o-stem pýr is more commonly attested)
  • Old Polish: pyrz (“couch grass”)
    • Polish: perz (“couch grass”)
  • Sorbian:
    • Upper Sorbian: pyŕ
    • Lower Sorbian: pyŕ

• Трубачёв, Олег Николаевич (a. 2002) Этногенез и культура древнейших славян (in Russian), Moscow: Наука, published 2003, →ISBN, pages 232–233, noting the identity of the meanings “fire remnants” and “spelt”.