co·in·ci·den·tal 
/koʊˌɪnsəˈdɛntl̟/ adjective
/koʊˌɪnsəˈdɛntl̟/ adjective [more coincidental; most coincidental] : happening because of a coincidence : not planned
▪ The fact that he and his boss went to the same college was purely/entirely/completely coincidental. ▪ a coincidental meeting
▪ The fact that he and his boss went to the same college was purely/entirely/completely coincidental. ▪ a coincidental meeting
— co·in·ci·den·tal·ly adverb
▪ Not coincidentally, they were both graduates of the same college.
▪ Not coincidentally, they were both graduates of the same college.
