This is an obsolete keyword which has not been printed in many years, it was last seen around the Ice Age block.

502.13. Cumulative Upkeep

• 702.21a. Cumulative upkeep is a triggered ability that imposes an increasing cost on a permanent. "Cumulative upkeep [cost]" means "At the beginning of your upkeep, put an age counter on this permanent. Then you may pay [cost] for each age counter on it. If you don't, sacrifice it." If [cost] has choices associated with it, each choice is made separately for each age counter, then either the entire set of costs is paid, or none of them is paid. Partial payments aren't allowed.
• 702.21b. If a permanent has multiple instances of cumulative upkeep, each triggers separately. However, the age counters are not connected to any particular ability; each cumulative upkeep ability will count the total number of age counters on the permanent at the time that ability resolves.

Rules Translation

• 702.21a. - This is something that becomes harder and harder to pay for. Use the age counters to track how expensive it is getting. If you don't pay the upkeep cost, sacrifice it.
• 702.21b. - Cumulative upkeep does stack, so you have multiple triggers.