Contradiction means a statement or situation where two things directly oppose or cancel each other out. When your friend says “I always tell the truth” but then admits she lied yesterday, that's a contradiction: both statements can't be true at the same time.

Contradictions reveal logical problems or inconsistencies. If someone claims they never eat sweets while munching on a candy bar, they're contradicting themselves. When a sign says “Always open” but lists closing hours underneath, that's a contradiction. Scientists look for contradictions in theories because if two parts of an explanation contradict each other, something must be wrong.

When you contradict someone, you're asserting the opposite of what they just said. If your teacher says it's going to rain and you say “Actually, the forecast shows sunshine all day,” you're contradicting them (politely, of course).

Some contradictions are serious logical errors, while others reflect changing circumstances: saying “I never liked broccoli” isn't really a contradiction if your tastes changed over time. But claiming “This box is completely empty” while it contains a ball is a genuine contradiction. Learning to spot contradictions helps you think more clearly and identify flaws in arguments.