pterygium
/tɛˈrɪdʒɪəm/noun
1 Ophthalmology. An abnormal triangular growth of fibrovascular tissue beneath the bulbar conjunctiva of the eye, typically having its base at the medial canthus and its apex towards or into the cornea, and often associated with excessive exposure to ultraviolet light.
2An abnormal condition of the nail in which the cuticle extends forward over the nail plate. More fully pterygium unguis.
3An abnormal web of skin, especially situated on the neck (more fully pterygium colli) or in the antecubital, popliteal, or interdigital regions.
Origin
Mid 16th century; earliest use found in William Bullein (c1515–1576), physician. From classical Latin pterygium morbid extension of the conjunctiva or cuticle, in post-classical Latin also any of various structures in anatomy named for a supposed resemblance to a wing from ancient Greek πτερύγιον little wing, fin, morbid extension of the conjunctiva (Hippocrates), in Hellenistic Greek also morbid extension of the cuticle, parts of the nose joining the cheeks from πτέρυγ-, πτέρυξ wing, fin + -ιον, diminutive suffix.