A flaw is an imperfection or weakness that makes something less than perfect. A crack in a diamond is a flaw. A spelling mistake in an otherwise excellent essay is a flaw. When scientists design an experiment but forget to account for an important variable, that oversight is a flaw in their method.

Flaws come in different forms. Some are physical: a scratch on a phone screen, a chip in a dinner plate, or a wobbly wheel on a skateboard. Others are less visible but just as real: a flaw in someone's argument might be a logical mistake that weakens their conclusion. A character flaw is a negative trait that causes problems for someone, like being quick to anger or refusing to admit mistakes.

The word often appears when something is mostly good but has one notable problem. You might say, “The plan was solid except for one fatal flaw,” meaning that single weakness could ruin everything. A flawed person isn't a bad person; they're simply human. Everyone has flaws.

Sometimes flawless describes something perfect: a flawless performance, a flawless victory, or a flawless gemstone.