APHASIA

aphasia [ uh-fey-zhuh ]
noun

Pathology.

1. an impairment of a previously held ability to produce or understand spoken, written, or signed language, due to disease or injury of the brain.

I had a friend who used to accuse me of having it (she did not have any medical education and was often admonished for bandying about diagnoses without any training). These days, she is not high on my friends' list.