"Radical" is an exemplary synonym for the word "radic". It denotes something fundamental or thorough in nature. Another suitable synonym is "profound", which encapsulates the idea of being deep or intense. Similarly, "revolutionary" serves as an appropriate substitute, highlighting ideas or movements that bring about significant changes. "Innovative" is another synonym that expresses the notion of being original and inventive. A more colloquial synonym would be "awesome", conveying the idea of something being remarkable or impressive. Overall, these synonyms aptly capture the essence of the word "radic" by representing its meaning through different shades of language and context.