The antonyms for the word "un-strengthened" are many and varied, depending on the context of usage. Some of the common antonyms include strengthened, fortified, reinforced, supported, bolstered, sustained, backed, enhanced, and empowered. Each of these words describes the opposite state, implying that the object or subject is in a better or stronger position. For instance, strengthened denotes a state of being physically or mentally stronger, sustained implies continued existence, while bolstered means to provide support or encouragement. Therefore, understanding the appropriate antonyms to use for "un-strengthened" is crucial, as it helps to clearly communicate an idea or message.