Aphasia (/əˈfeɪʒə/, /əˈfeɪziə/ or /eɪˈfeɪziə/), from ancient Greek ἀφασία (ἄφατος, ἀ- + φημί) aphatos meaning, “speechlessness”, derived from phat meaning “spoken” is a disturbance of the comprehension and formulation of language caused by dysfunction in specific brain regions.

This class of language disorder ranges from having difficulty remembering words to losing the ability to speak, read, or write. This also affects visual language such as sign language.

Aphasia is usually linked to brain damage, most commonly caused by stroke. Brain damage linked to aphasia can also cause further brain diseases, including cancer, epilepsy and Alzheimer's disease.

see Transient aphasia.

see Broca's aphasia