iron

• Russian
  желе́зоželezo

  ʐɨˈlʲezəinherited
• Ukrainian
  залі́зоzalizo

  zaˈlʲizɔinherited
• Polish
  żelazo

  ʐɛˈlazɔinherited
• Czech
  železo

  ˈʒɛlɛzoinherited
• Bosnian-Croatian-Serbian
  željezo / železoжељезо / железо

  ˈʒeʎezoinherited

  Standard-specific words: gvožđe (Serbian) — From *gvozdь 'nail'; the usual everyday Serbian word.

• English
  iron

Sound laws at work

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