The word "co-incidental" means occurring together by chance or in a way that cannot be predicted. Antonyms of "co-incidental" include "planned," "intentional," and "deliberate." These words imply that something is happening with purpose and forethought, rather than by chance. Other antonyms for "co-incidental" include "inevitable," "inevitable," and "predestined," which suggest that something is predetermined or bound to happen. Similarly, "systematic," "orchestrated," and "methodical" all mean that something is happening according to plan, rather than by chance. When looking for antonyms for "co-incidental," it's helpful to think about words that suggest intentionality or predictability.