A partition is something that divides space. When your younger brother decides to stop bathing, setting up a partition between his side of the room and yours seems like a good idea...until you realize your partition is not air-tight.
Partition can be used as a noun or as a verb. As a noun, it usually refers to a physical barrier between spaces. As a verb, to partition is to separate into sections — like to partition an office space into different work spaces. One can also partition something that does not involve physical space — like when you partition school life from home life, you are splitting your life into two parts that don’t intersect.