To subdivide means to split something that's already been divided into even smaller parts.

When a city grows, developers might subdivide large plots of land into smaller lots where individual houses can be built. A farm might be subdivided into separate fields for different crops. In math class, when you're working with fractions, you subdivide a half into quarters, then eighths, then sixteenths, creating tinier and tinier pieces.

The word often appears in real estate and urban planning. A subdivision is a neighborhood created when someone subdivides a large piece of property into many smaller parcels. You've probably seen subdivisions: residential areas where the streets, lot sizes, and houses often follow similar patterns because they were all planned and built around the same time.

Scientists subdivide topics into narrower categories to study them more carefully. A biology book might subdivide mammals into groups like primates, rodents, and cetaceans. Each time you subdivide, you're taking something already separated and breaking it down further, making the pieces more specific and detailed.