Extravasate is a term that refers to the leaking of fluid from a blood vessel or tissue outside the circulatory system. The opposite of extravasate would be to retain within a vessel or tissue, or to confine something to a particular space or location. Some examples of antonyms for extravasate include collect, contain, restrain, hold, maintain, and retain. In medical terminology, the term "insudate" is often used as an antonym for extravasate, which refers to an accumulation of fluid within a tissue or cavity. It's important to understand the meaning and usage of antonyms for words such as extravasate in order to better comprehend medical literature and terminology.