by the by

== English == === Alternative forms === by the bye, by-the-by, by-the-bye === Etymology === The second "by" is a noun meaning "a secondary issue". Phrase used since the 17th century. === Prepositional phrase === by the by Used to introduce a new topic; incidentally, by the way. ==== Translations ==== === Adjective === by the by (comparative more by the by, superlative most by the by) Incidental; unplanned. Synonyms: accidental, causeless, random; see also Thesaurus:accidental === See also === by the way === References === === Further reading === “by the by (or bye)”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.