An afterthought is something you think of or add later, after the main planning or action is already done. When you pack your backpack for school and then remember at the last second to grab your lunch from the kitchen, that lunch is an afterthought. When a teacher designs a lesson plan and then, just before class, decides to add a quick game at the end, that game is an afterthought.

The word often suggests that something wasn't given full attention or careful planning. If you're working on a group project and one member gets assigned a task as an afterthought, they might feel like their contribution wasn't really valued from the start. When someone treats you like an afterthought, they seem to remember you only after thinking about everything else first, which doesn't feel great.

Sometimes afterthoughts turn out to be surprisingly good ideas. A chef might add rosemary to a dish as an afterthought and discover it makes the recipe even better. But other times, treating important things as afterthoughts can lead to problems, like forgetting to study for a test until the last minute or leaving your best friend off the invitation list by accident.