Agenesis refers to the absence or underdevelopment of a body part or an organ. Synonyms for agenesis include aplasia, dysplasia, hypoplasia, and agamogenesis. Aplasia refers to the failure of a body part or an organ to develop during embryonic development. Dysplasia refers to abnormal development of a body part or tissue, while hypoplasia refers to underdevelopment of a part or organ that results in it being smaller than normal. Agamogenesis, on the other hand, refers to a condition in which an organism is formed without sexual reproduction. Understanding these synonyms can help in the accurate diagnosis and treatment of agenesis.