Real Dictionary

aphasia
uncountable noun: Aphasia is a mental condition in which people are often unable to remember simple words or communicate.

aphasia in American English
total or partial loss of the power to use or understand words, usually caused by brain disease or injury
noun: the loss of a previously held ability to speak or understand spoken or written language, due to disease or injury of the brain

aphasia in British English
noun: a disorder of the central nervous system characterized by partial or total loss of the ability to communicate, esp in speech or writing