Unrecognizable is an antonym for the word re-cognizable. It refers to something that is not easily identifiable or distinguished. Another antonym would be unfamiliar, which means having limited or no knowledge about something. A third option could be obscure, which relates to the notion of something being hidden or difficult to perceive. The word unintelligible could also function as an antonym, indicating a lack of clarity or meaning associated with the problem in question. In any case, understanding antonyms is a critical part of developing a comprehensive vocabulary and language skills.