the world > relative properties > relationship > [adverb] > in relation or with reference to or concerning > incidentally (5)
By the way, in passing, incidentally.
Phrases with a preposition. by the by is used parenthetically, with the omission of some phrase, such as ‘it may be remarked’. So by the way: see way…
By the way, in passing. Cf. obiter, adv.
In point of fact: used to accompany a not immediately pertinent statement.