Reconstruction:Proto-Slavic/reťi

• Per Vasmer, cognate with Lithuanian rẽkti (“to shout, to roar”), 1sg. rėkiù, Lithuanian rékauti (“to shout, to roar”), 1sg. rékauju, Latvian rèkt (“to shout, to roar, to howl”), rȩ̃kôt (“to talk, to chat”), as well as Sanskrit रचयति (racáyati, “to work, to construct”), Gothic 𐍂𐌰𐌷𐌽𐌾𐌰𐌽 (rahnjan, “to calculate”), Tocharian B reki, Tocharian A rake (“speech, word”), Latin raccō (“to roar (like a tiger)”), Old Irish réimm (“shout”), from Proto-Indo-European *rekmen.
• Per Derksen, possibly cognate with Sanskrit रचयति (racáyati, “to work, to construct”) and Welsh rhegi (“curse”).

*reťi[1]

1. to say

• *perdъreťi (“to predict”) < *perdъ (“front”) + *reťi
• *zareťi (“to order”) < *za (“for”) + *reťi
• *nareťi (“to nominate, to call”) < *na (“on”) + *reťi
• *otъreťi (“to deny, to renounce”) < *otъ (“from”) + *reťi
• *jьzreťi (“to utter, to proclaim”) < *jьz (“out of”) + *reťi
• *vъreťi (“to promise, to vow”) < *vъ(n) (“in”) + *reťi
• *sъreťi (“to spell syllables”) < *sъ(n) (“with”) + *reťi
• *rečenьcь (“term, deadline”) < *reťi + *-ьcь (compare *rokъ (“year”))

• *rāčìti (“to wish, want”)
• *rě̑čь (“speech”)
• *rokъ (“period of time”)
• *otrokъ (“child, servant”)
• *prorokъ (“prophet”)
• *porokъ (“vice, flaw”)
• *urokъ (“verbal agreement, curse, lesson”)
• *naročьnъ (“deliberate”)
• *uročьnъ (“agreed upon, accordant”)
• *rota (“oath”)

• East Slavic:
  • Old East Slavic: речи (reči)
    • Old Ruthenian: речи́ (rečí)
      • Belarusian: рачы́ (račý)
      • Ukrainian: речи́ (rečý), ректи́ (rektý)
    • Russian: речи́ (rečí) (dialectal)
• South Slavic:
  • Old Church Slavonic:

    Cyrillic: рещи (rešti)

    Glagolitic: ⱃⰵⱋⰹ (rešti)

  • Bulgarian: река́ (reká)
  • Serbo-Croatian:

    Cyrillic script: ре̏ћи

    Latin script: rȅći

    • Chakavian (Vrgada): rȅći
  • Slovene: réči (tonal orthography)
• West Slavic:
  • Old Czech: řéci
    • Czech: říct, říci
  • Polish: rzec
  • Slovak: riecť

• Vasmer, Max (1964–1973), “реку”, in Этимологический словарь русского языка [Etymological Dictionary of the Russian Language] (in Russian), transl. and suppl. by Oleg Trubachyov, Moscow: Progress
• Chernykh, P. Ja. (1993), “реку”, in Историко-этимологический словарь русского языка [Historical-Etymological Dictionary of the Russian Language] (in Russian), volume 2 (панцирь – ящур), 3rd edition, Moscow: Russian Lang., →ISBN, page 109
• Šanskij, N. M. (2004), “речь”, in Školʹnyj etimologičeskij slovarʹ russkovo jazyka [School Etymological Dictionary of the Russian Language] (in Russian), Moscow: Drofa

From earlier *regti, further etymology uncertain. Boryś derived descentands from *ręgati/*rǫgati (“to offend, to scorn”) and Brückner derived Slovene régniti from *ręžati (“to have a wide open mouth”). All ultimately from Proto-Indo-European *wreng- (“to twist, wring”). That makes missing nasal in Polish problematic.

Łuczyński proposed to derive it from Proto-Indo-European *h₁regʷ- (“to be dark”). For meaning shift from “dark, black” > “empty” compare Sanskrit रजस् (rajas, “darkness; space”), Tigrinya ፀሊም (ṣ́älim, “black, dark, empty”). The original Slavic meaning could therefore be “to make blanks”, which was narrowed down to “to cut”.

*reťi impf[1]

1. to cut, crack

• South Slavic:
  • Croatian:
    • Kajkavian: regani (“notched, with cracks”) (passive participle from *regati)
      • ⇒ Kajkavian: *rega
        • ⇒ Kajkavian: regast (“corrugated”)
    • ⇒ Shtokavian: regánac (“incised lace”)
  • Slovene: régati (“to crack”), rẹ́gniti (“to burst, open up”)
    • ⇒ Slovene: réga
      • ⇒ Slovene: régast
• West Slavic:
  • Polish: *rzegać
    • ⇒ Polish: rzega (“streak, weal, welt”) (dialectal)

• Brückner, Aleksander (1927), “rzężeć”, in Słownik etymologiczny języka polskiego [Etymological Dictionary of the Polish Language] (in Polish), Warsaw: Wiedza Powszechna
• Snoj, Marko (2016), “regniti”, in Slovenski etimološki slovar³ (in Slovene), https://fran.si
• Wiesław Boryś (1992), “rzega”, in Stanisław Urbańczyk, editor, Język polski‎ (in Polish), volume 72, Kraków: Towarzystwo Milosnikow Jezyka Polskiego, page 28