Is it ensure, insure, or assure?
early 15c., "division into shares, distinction," from Old French particion (12c.), from Latin partitionem (nominative partitio) "a sharing, division, partition, distribution; method of dividing," from past participle stem of partire "to part" (see part (v.)). Sense of "that which separates" first recorded late 15c.
1741, from partition (n.). Related: Partitioned; partitioning.
partition par·ti·tion (pär-tĭsh'ən)
The act or process of dividing something into parts.
The state of being so divided.
A wall, septum, or other separating membrane in an organism.