break-off vs parenthesis

break-off

noun
  • A break, discontinuance, or interruption 

  • That which breaks off, or is broken off 

  • The first shot in a game of snooker or other cue-game 

verb
  • To play the first shot in a game of snooker 

parenthesis

noun
  • A digression; the use of such digressions. 

  • A clause, phrase or word which is inserted (usually for explanation or amplification) into a passage which is already grammatically complete, and usually marked off with brackets, commas or dashes. 

  • Such brackets as used to clarify expressions by grouping those terms affected by a common operator, or to enclose the components of a vector or the elements of a matrix. 

  • Either of a pair of brackets, especially round brackets, ( and ) (used to enclose parenthetical material in a text). 

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