The text defines several linguistic terms:

*   **Wernicke’s Aphasia**: Fluent, meaningless speech; severe comprehension loss from Wernicke’s area.
*   **Anomic Aphasia**: Word retrieval difficulty; grammar/comprehension intact.
*   **Conduction Aphasia**: Impaired repetition; preserved comprehension, production.
*   **Alexia**: Reading disorder; cannot recognize written words despite intact vision.
*   **Agraphia**: Writing ability loss due to brain damage.
*   **Language Modality**: Four basic uses: speaking, listening, reading, writing.
*   **Language Disorder**: Impairment in language comprehension or production.
*   **Error Analysis**: Systematic study of learner errors to understand language learning.
*   **Contrastive Analysis**: Compares languages to predict learning difficulties.
*   **Interlanguage**: Evolving linguistic system of language learners.