Antonyms for the word "ante date" can be understood as words that are opposite in meaning to "ante date." One possible antonym for "ante date" could be "postdate," which refers to a date that comes after another date. Whereas "ante date" refers to a date that comes before another date, "postdate" refers to a date that comes after another date. Another antonym for "ante date" could be "current," which means happening or existing now. This is because "ante date" refers to a date that is in the past, while "current" refers to something in the present.