A [hordeolum] is an inflamed Meibomian gland (also known as a tarsal gland). These glands are found at the edge of the eyelids and their lipid product (meibum) helps seal the eyes and prevent tear evaporation. The vernacular term for an hordeolum is "stye" or "sty".

The term arises from the Latin [hordeum] meaning "barley". It refers to the appearance of the inflamed gland to a barleycorn. The eponymic term "Meibomiam gland" honors Heinrich Meibom (1638-1700), a German anatomist who first described the tarsal glands of the eye.

The removal of a hordeolum is called a "hordeolectomy"

Image courtesy of Wikipedia

Five-day old hordeolum