WordNet sense 1 (a vertical structure that divides or separates (as a wall divides one room from another)):

divider

WordNet sense 2 (divide into parts, pieces, or sections):

partition off

WordNet sense 3 (the act of dividing or partitioning; separation by the creation of a boundary that divides or keeps apart):

division, segmentation, partitioning, sectionalisation, sectionalization

WordNet sense 4 (separate or apportion into sections):

zone