once in a while vs singularly

once in a while

adv
  • Occasionally; sometimes. 

singularly

adv
  • Strangely; oddly. 

  • In the singular number; in terms of a single thing. 

  • solely; only; uniquely 

  • Extremely; remarkably. 

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