Synonyms of incidentally in English:

incidentally


See US English definition of incidentally

See UK English definition of incidentally

adverb

1‘incidentally, I haven't had a reply from Hartley yet’

SYNONYMS
by the way, by the by, by the bye, in passing, en passant, speaking of which, while on the subject
parenthetically
informal BTW, as it happens

2‘the infection was discovered incidentally at post-mortem examination’

SYNONYMS
by chance, by accident, accidentally, fortuitously, by a fluke, as luck would have it, by a twist of fate
coincidentally, by coincidence
North American by happenstance