spurious
False but made to seem real or believable at first.
Spurious means false or fake, but in a way that might fool people at first because it looks or sounds legitimate. A spurious argument seems convincing until you examine it closely and realize it's based on bad logic or false information. A spurious claim appears true on the surface but falls apart under scrutiny.
The word often describes things that pretend to be something they're not. If someone draws a spurious connection between two events, they're claiming the events are related when they actually aren't. For example, noticing that you wore your lucky socks on days you got good grades, then insisting the socks caused the good grades, creates a spurious link between two unrelated things.
Scientists worry about spurious data: measurements that look real but are actually caused by equipment problems or experimental errors. A detective investigating a crime must separate genuine clues from spurious ones that only seem relevant. In everyday life, you might encounter spurious reasons, spurious excuses, or spurious explanations: things that sound plausible but don't hold up when you think them through carefully.
Unlike an obvious lie, something spurious has enough surface credibility to temporarily deceive people who aren't paying close attention or who don't have all the facts.