The word "un-defended" refers to something that is vulnerable, open or exposed. Therefore, its antonyms are words that imply strength, protection or security. Examples of antonyms for the word "un-defended" include protected, guarded, fortified, secured, shielded, sheltered, defended, fortified, and safe. These words all denote a sense of safety or security, which is the complete opposite of the meaning associated with "un-defended". It's essential to use the correct antonyms when writing to ensure clarity and precision in communication. Therefore, understanding antonyms is a crucial element of the English language that can help writers convey their intended message effectively.