'aphasic' originates from medical English, specifically from the noun 'aphasia', which ultimately comes from Greek 'ἀφασία' (aphasia), where the prefix 'a-' meant 'without' and 'phasis' (from phasis) meant 'speech' or 'utterance'.

'aphasic' was formed in English in the late 19th century by adding the adjective-forming suffix '-ic' to 'aphasia'; 'aphasia' itself entered medical usage from Greek ἀφασία through Late Latin and European medical terminology into modern English.

Initially the Greek root elements meant 'without speech'; over time the term became a clinical term referring to loss or impairment of language function, and 'aphasic' came to mean 'relating to or a person affected by aphasia'.