co ‧ in ‧ ci ‧ den ‧ tal AC /kəʊˌɪnsəˈdentl, kəʊˌɪnsɪˈdentl $ koʊ-/ BrE AmE adjective
happening completely by chance without being planned ⇨ coincidence
purely/completely/entirely coincidental
Any similarity between this film and real events is purely coincidental.
—coincidentally adverb [sentence adverb] :
We have become profitable. Not coincidentally, we have only half as many employees as we did in 1988.