mudguard vs protector

mudguard

noun
  • A cover over the wheels of a vehicle, or a flap behind that wheel, to prevent water and mud being projected. 

protector

noun
  • A device or mechanism which is designed to protect. 

  • A state or other subject under international law, exercising a protectorate over another subject in international law. 

  • One having the care of the kingdom during the king's minority; a regent. 

  • One who prevents interference. 

  • A cardinal, from one of the more considerable Roman Catholic nations, who looks after the interests of his people at Rome; also, a cardinal who has the same relation to a college, religious order, etc. 

  • Someone who protects or guards, by assignment or on their own initiative. 

How often have the words mudguard and protector occurred in a corpus of books? (source: Google Ngram Viewer )