# by the by

> English word · Prep_phrase

## Definitions
1. Used to introduce a new topic; incidentally, by the way.

## Etymology
The second "by" is a noun meaning "a secondary issue". Phrase used since the 17th century.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-09-03.
Canonical page: https://plainspell.com/en/word/by-the-by