Which of the following terms represents a dilation or expansion?

The term that represents dilation or expansion is indeed "-ectasis." This suffix is derived from the Greek word "ektasis," which means expansion or dilation. It is commonly used in medical terminology to describe conditions where there is an abnormal enlargement of a structure or organ. For example, bronchoectasis refers to the abnormal dilation of the bronchi, which can occur due to various underlying conditions.

Understanding this term is essential for interpreting medical reports and descriptions of various conditions relevant to oncology and other medical fields. The context in which "-ectasis" is used helps healthcare professionals assess the extent and implications of diseases involving dilated structures. The precise use of language is vital for clear communication among healthcare providers and for understanding patient diagnoses and treatment options.