кра

According to Sreznevsky from Proto-Slavic *kъra. Akin to Old Czech kra (“piece of rock or other material”).

кра (kra) ?

1. floe, thin ice, piece

• криниѥ (krinije)

• Old Ruthenian: крига (kriha)
  • Belarusian: кры́га (krýha)
    • → Polish: kryha
  • Rusyn: кри́га (krýha, “ice”)
  • Ukrainian: кри́га (krýha, “ice”)
    • → Slovak: kryha
  • → Russian: кри́га (kríga), кры́га (krýga) (dialectal)

• Sreznevsky, Izmail I. (1893), “кра”, in Матеріалы для Словаря древне-русскаго языка по письменнымъ памятникамъ [Materials for the Dictionary of the Old East Slavic Language Based on Written Monuments]‎ (in Russian), volume 1 (А – К), Saint Petersburg: Department of Russian Language and Literature of the Imperial Academy of Sciences, column 1310
• Sreznevsky, Izmail I. (1893), “криниѥ”, in Матеріалы для Словаря древне-русскаго языка по письменнымъ памятникамъ [Materials for the Dictionary of the Old East Slavic Language Based on Written Monuments]‎ (in Russian), volume 1 (А – К), Saint Petersburg: Department of Russian Language and Literature of the Imperial Academy of Sciences, column 1324
• Sreznevsky, Izmail I. (1912), “къра”, in Матеріалы для Словаря древне-русскаго языка по письменнымъ памятникамъ [Materials for the Dictionary of the Old East Slavic Language Based on Written Monuments]‎ (in Russian), volume 3 (Р – Ꙗ и дополненія), Saint Petersburg: Department of Russian Language and Literature of the Imperial Academy of Sciences, column 1840