Variation Margin
A variable margin payment that is made by clearing members to their respective clearing houses based upon adverse price movements of the futures contracts that these members hold.
Investopedia Commentary
Variation margin is paid by clearing members on a daily or intraday basis in order to reduce the exposure created by carrying highly risky positions. By demanding variation margin from its members, clearing organizations are able to maintain a suitable level of risk and cushions against significant devaluations.
See also: Clearing, Clearing House, Intraday, Leverage, Maintenance Margin, Margin, Margin Call