The word "fore warns" means to give a warning or an advance notice about something. The opposite or antonym of "fore warns" would be to remain silent, conceal or withhold information, or simply not give any warning at all. Another antonym of "fore warns" could be to encourage or promote something instead of warning against it. In other words, the opposite of "fore warns" is to take no action, to keep quiet, or to promote something without warning about its potential risks or drawbacks. So, it is essential to consider both the warning and the opposite action when making decisions about important matters.