Enforceable is the state where a law or a contract can be upheld and implemented. Therefore, un-enforceable antonyms are those that mean something that is not legally binding or cannot be carried out. Possible antonyms of un-enforceable could include valid, effective, binding, enforceable, and legal. These words connote a sense of having power, authority, or legitimacy, and they suggest that whatever is in question is capable of being enacted, sanctioned or enforced. Examples of how these opposites might be used in context include "valid agreement," "enforceable contract," "legal obligation," "binding resolution," and "effective law." By using these antonyms, one can convey the opposite meaning of un-enforceable in a clear and concise way.