if only vs only

if only

conj
  • Even if for no other reason than; only just. 

  • Used other than figuratively or idiomatically: see if, only. 

  • I wish that; signifies a wish or desire for the present or the future. 

  • I wish that; signifies a regret about an action in the past. 

only

conj
  • But; except. 

  • Under the condition that; but. 

adj
  • Alone in a category. 

  • Singularly superior; the best. 

  • Without sibling; without a sibling of the same gender. 

adv
  • As recently as. 

  • Without others or anything further; exclusively. 

  • Used to express surprise or consternation at an action. 

  • Introduces a disappointing or surprising outcome that renders futile something previously mentioned. 

  • No more than; just. 

noun
  • An only child. 

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