The antonyms for the word "un-guarded" are many, and they include words such as guarded, cautious, vigilant, watchful, careful, defended, protected, safe, secure, and shielded. Guarded and cautious both imply a mindset of being careful and taking necessary precautions to avoid any potential harm or danger. Vigilant and watchful suggest a keen sense of awareness to detect any possible threats. Defended, protected, safe, secure, and shielded all suggest a level of safety and protection from harm or danger, whether physical or emotional. In any case, these antonyms all reflect the importance of being careful and taking measures to protect oneself from harm.