Why was "tantrum" trending last week?
pertaining to two diseases which occur together, such as ADHD and depression
1985, from co- "along with" + morbidity "diseased condition." Comorbid (adj.) is a 1990 back-formation.
comorbidity co·mor·bid·i·ty (kō'môr-bĭd'ĭ-tē)n. A concomitant but unrelated pathological or disease process.