defectless vs foolproof

defectless

adj

  • without a defect 

foolproof

verb

  • To render foolproof. 

adj

  • Certain to succeed in all eventualities, or claimed to be so; infallible. 

  • Protected against, or designed to be proof against, misuse or error. 

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