fallacious (adj) – misleading; deceptive in meaning; based on a fallacy
BREAKDOWN: FAL- (deceive) + -ACIOUS (inclined to)
— a fallacy is a false notion, a mistaken idea, or a statement that contradicts fact
This word is built on the root FAL-, which means to fail or to deceive.
Common FAL- words include fault, fail, failure, false, and falsehood.
More esoteric FAL- words include fallibility.