Definition: The Greek word 'aphasia' has two meanings: 1) Speech loss or incapacity, especially in oneβs language. 2) Loss of understanding or ability to comprehend or understand something. Detailed definition: 1) Speech loss or incapacity, especially in oneβs language: - The inability to produce speech. 2) Loss of understanding or ability to comprehend or understand something: - A lack of comprehension (understanding), usually due to the absence of words or their incorrect interpretation or meaning.