Sties are small, painful bumps that appear on the eyelids and often cause discomfort. Some common synonyms for sties include hordeolum, an abscess caused by infection of a gland in the eyelid, or chalazion, a bump caused by a blocked oil gland. Other related terms include conjunctivitis, inflammation of the conjunctiva, and blepharitis, which is inflammation of the eyelids. If left untreated, sties can develop into more serious conditions, such as cellulitis or a systemic infection. Therefore, it is important to seek medical attention if you suspect you have a sty or any related eye condition.