Flaw
In psychology, a flaw was a weakness or imperfection in a theory, research study, or a person's character.
In 2267, the Earth probe Nomad was declared flawed by Captain James T. Kirk. (TOS: "The Changeling")
In 2371, Captain Kathryn Janeway chastised Lieutenant Tuvok for using logic to justify having gone against her orders. She told him that one could use logic to justify anything, that this was its power, but also its flaw and that he should from now on first bring his logic to her. He agreed that while his logic was not in error, he was. (VOY: "Prime Factors")