The antonyms for the word "in-defectible" are many and varied. Some of the most common antonyms for this word include flawed, imperfect, deficient, defective, fallible, erroneous, and faulty. Each of these words describes the opposite of the meaning of "in-defectible," which means "incapable of being defective or flawed." When we use an antonym to describe something as flawed or imperfect, we are acknowledging that it has faults or defects that need to be addressed. By contrast, when we use the word "in-defectible," we imply that something is flawless and cannot be improved upon.