flaw

an imperfection in an object or machine; "a flaw caused the crystal to shatter"; "if there are any defects you should send it back to the manufacturer"

defect or weakness in a person's character; "he had his flaws, but he was great nonetheless"

an imperfection in a plan or theory or legal document that causes it to fail or that reduces its effectiveness

add a flaw or blemish to; make imperfect or defective