mudguard

/ˈmʌdɡɑrd/
noun
  1. A curved piece of metal or plastic over a wheel of a bicycle, motorcycle, or vehicle that prevents mud and water from splashing up.
    • The car's mudguard was dented after hitting a rock on the dirt road.
    • I need to tighten the mudguard on my bike because it's rattling.
    • She wiped the mud off the mudguard before parking her motorcycle in the garage.
Synonyms