happening by chance; not planned I suppose your presence here today is not entirely coincidental. It's purely coincidental that we both chose to name our daughters Emma.
NAmE//koʊˌɪnsəˈdɛntli//, NAmE//koʊˌɪnsəˈdɛntəli//
adverb Coincidentally, they had both studied in Paris.See coincidental in the Oxford Advanced Learner's DictionaryCheck pronunciation: coincidental