off duty vs skiving

off duty

prep
  • Not engaged in an assigned task, duty or occupation. 

skiving

noun
  • A piece made in skiving (paring or splitting) leather, especially the part from the inner, or flesh, side. 

  • A type of machining that skives metal, with various applications including gear cutting. 

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