1. Aphasia - impaired speech and language perception
2. Apnea - cessation of breathing
3. Appendicitis - inflammation of the appendix; removal of the appendix is an appendectomy
4. Arthritis - inflammation of a joint
5. Asthma - difficulty breathing because air cannot be efficiently expelled
6. Astigmatism - loss of image sharpness that causes eyes to tire easily
7. Ataxia - walking problems result from the lack of muscle coordination
8. Atrophy - wasting away of muscle or organ
9. Audiogram - hearing test
10. Aura - often precedes migraine headache or seizure
11. Avascular necrosis (osteonecrosis) - bone death