By the way Meaning, Definition & Usage

  1. adverb introducing a different topic; in point of fact
    by the bye; incidentally; apropos.
    • incidentally, I won't go to the party

WordNet


Definitions
  1. by the bye; used to introduce an incidental or secondary remark or subject. -
Definitions
  1. in passing; apropos; aside; apart from, though connected with, the main object or subject of discourse.

Webster 1913