piddling vs unfrequent

piddling

adj
  • Insignificant, negligible, paltry, trivial, useless. 

unfrequent

adj
  • Not frequent; not common; not happening often; infrequent. 

verb
  • To stop frequenting; cease to frequent. 

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