Main Entry: in·ci·den·tal·ly

Pronunciation: \-ˈden-t^əl-ē, especially for 2 -ˈdent-lē\

Function: adverb

Date: 1665

1 : in an incidental manner : not intentionally <the arrant nonsense of some of his statements is incidentally hilarious — John Lahr>
2 : by way of interjection or digression : by the way <fortunate in having a good teacher…—still living, incidentally — John Fischer>