The phrase "forewarned" implies prior knowledge or warning about a situation. Its antonym would be "uninformed" or "unforewarned." This means a lack of knowledge or warning about something, leaving someone vulnerable to potential negative consequences. Another antonym for "forewarned" would be "surprised" or "caught off guard," indicating a sudden and unexpected event for which there was no prior warning. In essence, being forewarned can give someone an advantage, whereas being uninformed or surprised can put them at a disadvantage. Thus, it is always better to be forewarned and prepared for any uncertainties that may arise.