Other forms: epexegeses
An epexegesis adds words to clarify the meaning of other words. In other words, it's the addition of details or extra info to make something clearer — just as this sentence is an epexegesis of the previous one.
Think of an epexegesis as added information. It could be just a few words set off by commas, parentheses, or dashes within a sentence: e.g., "He had an aquiline nose — meaning it curved down like an eagle's beak." Or it could be a whole other sentence immediately following the first. The word comes from two Greek elements, epi- (meaning "in addition") and exegesis (meaning "explanation").