What's the correct medical term for an abnormality in tissue development?

The term for an abnormality in tissue development is best described by the option identified. Hypoplasia refers specifically to an incomplete or underdevelopment of a tissue or organ, resulting in a decreased number of cells. This condition represents a failure of normal development and growth, which distinctly characterizes the abnormality in tissue development highlighted in the question.

Aplasia, while related to tissue development, denotes a complete absence of the tissue or organ rather than an underdevelopment. Neoplasia refers to the process of new, abnormal growth, typically associated with tumors. Metaplasia involves the transformation of one type of cell into another, often as a response to chronic irritation or inflammation. This kind of change does not directly describe an abnormality in tissue development in terms of overall size or number, making hypoplasia the most accurate term in this context.