The term "un-susceptible" means resistant or immune to something. To find the antonyms of "un-susceptible," we need to look for words that mean the opposite of resistant. In this case, the antonyms of "un-susceptible" are words like vulnerable, receptive, responsive, sensitive, and susceptible. These words imply that a person or thing can be impacted by an external stimulus or force. For instance, someone who is susceptible to flattery can be easily influenced by it. Similarly, a disease-prone person is vulnerable to catching sicknesses. Therefore, by using antonyms of un-susceptible, we can convey the opposite meaning, which is being prone to or affected by something.