assessor vs invigilator

assessor

noun
  • A specialist who assists the court in determining a matter. 

  • One who assesses a project for cost evaluation. 

  • A civil servant entrusted with checking the veracity of data and criteria used by a taxpayer to complete a tax return. 

  • An official responsible for student welfare. 

  • One who assesses a property for tax or insurance evaluation. 

invigilator

noun
  • A person who supervises students during an examination; a proctor 

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