light

• Russian
  светsvet

  svʲetdifferent word · Proto-Slavic *světъ 'light, world', the root noun of *světlo

  Russian светлый 'bright' shows the *světl- stem.

• Ukrainian
  сві́тлоsvitlo

  ˈsʋʲitlɔinherited
• Polish
  światło

  ˈɕfjatwɔinherited
• Czech
  světlo

  ˈsvjɛtloinherited
• Bosnian-Croatian-Serbian
  svjetlo / svetloсвјетло / светло

  ˈsvjetloinherited
• English
  light

Sound laws at work

• Jat (ě) and its reflexes
• Polish vowel ablaut (ě → a, e → o)
• Ukrainian і (ikavism)