Sulcus subtarsalis refers to a groove located on the inner side of the eyelid where the tarsal plate meets the conjunctiva. This structure is crucial in the formation of the tear film and, therefore, has several synonyms used in ophthalmology. Some of these include subtarsal sulcus, tarsal conjunctival sulcus, inferior tarsal sulcus, and caruncular sulcus. Anatomically, the sulcus subtarsalis is a narrow depression that forms a boundary between the palpebral and bulbar conjunctiva. Understanding the various synonyms associated with this structure is vital for medical professionals, especially those involved in the diagnosis and treatment of eye disorders.