The phrase "out window" implies something that is outside or beyond a window. Antonyms for this term can include "inside" or "indoors." Other antonyms might be more specific to the context in which the phrase is used. For example, in a context where "out window" refers to a missed opportunity or lost chance, antonyms could include "seize," "grab," or "take advantage of." Alternatively, if "out window" is being used to describe something that is outside of someone's knowledge or awareness, antonyms might include "know," "understand," or "be aware of." Ultimately, the most effective antonyms for "out window" will depend on the specific meaning and usage of the phrase in a given context.