A blemish is a mark or flaw that makes something less perfect than it could be. When you have a blemish on your skin, like a pimple or small scar, it's a spot that stands out from the rest. A blemish on an apple might be a brown bruise or discolored patch that makes it look less appealing, even though the fruit is still perfectly good to eat.

The word often describes physical marks, but it can also describe damage to someone's reputation or record. A student with a spotless academic record has no blemishes: no missing assignments, no disciplinary problems, nothing to mar their history. But one incident of copying homework could be a blemish on that record.

The interesting thing about blemishes is that they're usually small compared to the whole thing. A tiny blemish on a beautiful painting doesn't ruin the entire artwork, just as one mistake doesn't define a person's character. Still, we notice blemishes precisely because they interrupt something that would otherwise be smooth, clean, or perfect. When something is unblemished, it means completely free from marks or flaws.