English Reference
Noun

complication

n. C / U
C1 Advanced Oxford US /ˌkɑmpɫəˈkeɪʃən/ UK /kˌɒmplɪkˈeɪʃən/ com·pli·ca·tion UK spelling complications Medicine

n.a new problem that makes a situation more difficult to deal with. In medicine, it is a second illness or medical problem that happens while you are already sick.

n.a secondary disease or condition aggravating an already existing one; more generally, a factor that makes a situation more complex or difficult to resolve.


SIMPLE

The surgery was successful and there was no complication.

CONTEXTUAL

The doctor explained that the patient's high blood pressure could lead to a serious complication during the recovery process.

COMPLEX

While the initial plan seemed straightforward, the sudden resignation of the lead architect introduced a complication that the project management team had not anticipated in their risk assessment.

Usage

Often used with the verbs 'arise' or 'develop'. In its medical sense, it is frequently used in the plural to describe post-operative risks.

Severe complications , like pneumonia or brain swelling, can lead to hospitalization and death.

The Guardian· 13 Aug 2026

UN Humanitarian Coordinator for Afghanistan Bruno Lemarquis  said  funding gaps could, among other things, force health centre closures, “leaving thousands of mothers and newborns vulnerable to preventable complications and death”.

UN News· 12 Aug 2026

Common in science and health writing

This entry
Level C1 · Advanced
Frequency Frequent
Updated