Final answer:
Exophthalmos is an abnormal protrusion of eyeballs due to edema behind the eye usually associated with hyperthyroidism and is a symptom of Graves' disease.
Step-by-step explanation:
The term for an abnormal protrusion or bulging outward of the eyeballs due to edema behind the eye, usually associated with hyperthyroidism, is exophthalmos. Exophthalmos is a common symptom of hyperthyroidism, particularly Graves' disease, and is characterized by the eyes appearing to bulge out from the face. This condition is caused by swelling of the tissues behind the eyes due to accumulated fluid caused by thyroid dysfunction.