Defendability is the quality of being justifiable or logically valid. Its antonyms are the terms that describe qualities that contradict this state. These include unjustifiable, indefensible, fallacious, illogical, unsound, weak, and flimsy. Something that lacks defendability cannot be justified or explained in a way that stands up to scrutiny. It may be based on false assumptions or logical fallacies, or it may simply lack strong evidence or reasoning to support it. In contrast, something that has strong defendability is supported by logical, factual, or ethical foundations that can be defended against criticism or challenge.