A flake is someone who agrees to do something but doesn't follow through, often canceling at the last minute or simply not showing up. When your friend promises to come to your birthday party but texts an hour before saying they can't make it (again), they're being a flake. When a teammate says they'll help with the group project but never does their part, they're flaking out.

The word can also describe the behavior itself: someone might flake on their commitments or flake out on plans. Being a flake is different from having a genuine emergency once in a while. Everyone faces unexpected problems sometimes. A flake is someone who makes this a pattern, leaving others waiting, disappointed, or scrambling to adjust.

The word also describes a thin, flat piece that breaks off from something larger, like a snowflake or a flake of paint peeling off a wall. When you pour cereal into a bowl, many kinds are made of flakes: thin, crispy pieces. A flaky pie crust breaks apart into delicate layers.

Just as paint flakes fall off when they lose their bond to the wall, a flake as a person fails to maintain their connection to their commitments.