The term "un-strengthen" implies to weaken. The antonyms for un-strengthen are strength, reinforce, and fortify. These words have the opposite meaning of un-strengthen, which is to make someone or something stronger. If you want to enhance your physical or mental strength, you should exercise regularly, have a balanced diet, and get enough rest. Similarly, it is equally important to strengthen the relationships you have with people. Communication, trust, and mutual respect fortify lasting and robust relationships. By strengthening yourself physically, mentally, and emotionally, you can lead a fulfilling and healthy life.