The term "ex postulate" refers to a proposition or assumption based on subsequent analysis or observation. Antonyms for "ex postulate" include "a priori" which connotes an assumption that is made prior to any evidence or observation, "speculation" which refers to conjecture or guesswork, and "unfounded" which implies that the proposition or assumption is not based on any logical foundation. Other antonyms for "ex postulate" may include terms such as "hypothesis" which is a proposed explanation or theory that is subject to testing, "conjecture" which is a guess based on incomplete information, or "preconception" which refers to a pre-existing idea or belief that may influence subsequent analysis or observation.