The gland of Zeis is a small sebaceous gland found in the skin of the eyelid. It is responsible for producing sebum, a waxy substance that helps to moisturize and lubricate the eyelashes. There are several synonyms for the gland of Zeis, including tarsal gland, meibomian gland, and oil gland. These glands are also located in the eyelid and produce oils that are important for the health and function of the eye. While these synonyms are commonly used interchangeably, they refer to slightly different types of glands and may have unique functions within the eye.