com·pli·ca·tion / ˌkämpləˈkāshən/ • n. 1. a circumstance that complicates something; a difficulty. ∎  an involved or confused condition or state: to add further complication, English speakers use a different name.2. Med. a secondary disease or condition aggravating an already existing one: she developed complications after the surgery.

complication (kom-pli-kay-shŏn) n. a disease or condition arising during the course of or as a consequence of another disease.