Previous means coming before something else in time or order. If you're reading chapter five of a book, the previous chapter was chapter four. If today is Wednesday, the previous day was Tuesday. When a teacher asks “Does anyone remember what we learned in the previous lesson?” she's asking about what happened in the class before this one.

The word helps us talk about sequences and connections between events. A scientist might compare her current experiment to previous experiments to see what changed. A soccer coach might study film from previous games to help the team improve. When you're following directions and they mention a previous step, they're pointing you back to something you already did.

Previous is the opposite of next or following. Notice how it always needs context: something can only be previous to something else. Your previous birthday wasn't just any birthday, it was the one right before your current age.