Bunch up, a phrase that means to gather closely or squeeze together, has several antonyms or words with opposite meanings. The first antonym is spread out, which suggests a wide distribution or scattering of things. Another antonym is loosen up, which implies relaxing or becoming less rigid or tense. Disperse is another antonym that indicates a wider distribution of things. Separate and disjoin are other antonyms that suggest breaking something down into individual components or parts. Finally, open up entails creating more space or expanding a space, while relax suggests reducing tension or anxiety. These antonyms help to create a more nuanced understanding of the meaning of the phrase 'bunch up.