Reconstruction:Proto-Slavic/krękъ

• *krekъ, *skrekъ (attested in West Slavic)
• *krěkъ (attested in South Slavic)

Disputed:

• Berneker, Bezzenberger, Kroonen: Of etymological origin, akin to Proto-Slavic *kręčь, *kręky (“plank, rod”) and *kręgъ, *kręžь (“ridge, hump”); possibly further related to Lithuanian kurkulai̇̃ pl (“frog spawn”), Latvian kurkul̨i pl (“frog spawn”), Proto-Germanic *hrugnaz (“roe”). Perhaps from a nasal extension of Proto-Indo-European *(s)ker-, *(s)kreh₁- (“to perturb, to pound, to swing”). For the semantic shift, compare analogous Latin plangō (“to strike”) → Latin plāga (“stroke; plague”), possibly planta (“plant”).
• Machek, Trubačev: Of onomatopoeic origin, akin to Proto-Slavic *krekъ, *krěkъ, *krakъ (“squawk, quack”).

ESSJa formally distinguishes between meanings “spawn” (under *krękъ I) and “sprout” (under *krękъ II).

*krękъ m

1. spawn, sprout

   → frog spawn (mainly in East Slavic, attested in derivatives within other branches)

   Synonym: *jьkra (“roe”)

   → offshoot, bough, bole of plant (in South Slavic)

   Synonyms: *bъtvo, *bоturь

   → turf of aquatic vegetation (in Serbo-Croatian, Sorbian)

• *kręčina (“spawn, colony”)
• *krękosъ (“spawner”)

• *kory (“root”)
• *kręčь, *kręky (“plank, rod”)
• *krękati (“to curl, to change course”)
• *krętati (“to move, to change position”)

• East Slavic:
  • ⇒ Belarusian: кракові́на (krakovína, “sedimentation”) (dialectal)
  • Russian: кряк (krjak, “spawn; trunk”) (standard); крёк (krjok, “frog spawn”) (dialectal)
    • ⇒ Russian: укря́к (ukrják, “frog spawn”)
• South Slavic:
  • Serbo-Croatian: (conflated with *krěkъ)

    Cyrillic script: кре̑к (“sprout, bole”) (dialectal), о̏кријек (“duckweed”)

    Latin script: krȇk (“sprout, bole”) (dialectal), ȍkrijek (“duckweed”)

  • Slovene: krẹ́k, krȃk (“spawn”) (dialectal)
    • ⇒ Slovene: žabokrẹ́čina (“frog spawn”)
• West Slavic:
  • Czech: skřek (obsolete)
    • ⇒ Czech: žаbоkřеkу pl (“frog spawn”)
  • Polish: krzek, skrzek (“amphibian spawn”)
  • Sorbian:
    • Lower Sorbian: kśek (“water plant”)
    • Upper Sorbian: křek (“water plant”)

• Vasmer, Max (1964–1973) “кряк”, in Oleg Trubachyov, transl., Этимологический словарь русского языка [Etymological Dictionary of the Russian Language] (in Russian), Moscow: Progress
• Trubachyov, Oleg, editor (1985), “*krękъ I, II”, in Этимологический словарь славянских языков [Etymological dictionary of Slavic languages] (in Russian), numbers 12 (*koulъkъ – *kroma/*kromъ), Moscow: Nauka, page 144
• “kurkulai”, in Lietuvių kalbos etimologinio žodyno duomenų bazė [Lithuanian etymological dictionary database], 2007–2012
• Kroonen, Guus (2011) The Proto-Germanic n-stems: A study in diachronic morphophonology, Amsterdam, New York: Rodopi, →ISBN, page 171