To expel means to force someone or something out of a place, often officially or permanently. When a school expels a student, it means that student is no longer allowed to attend because they broke serious rules. When a country expels a diplomat, it's ordering that person to leave and not return.

The word carries a sense of authority and finality. A teacher might send a disruptive student to the principal's office temporarily, but expelling them means they can't come back to that school at all. It's a serious consequence, not a minor punishment.

Your body can also expel things naturally. When you cough, your lungs expel air forcefully to clear irritation. When you exhale, you expel carbon dioxide.

Someone who has been expelled is called an expellee. The process itself is called expulsion.