ground rule 
noun
1 (usually ground rules) A basic principle: some ground rules for assessing new machines...
- Before an interview, Johnson laid down the ground rule that he didn't want to talk about his Seattle days.
- My first ground rule is always to tell the truth.
- The ground rule on that subject would be never to make familiarity with one's earlier works necessary for enjoying or appreciating the current one.
2 Baseball A rule relating to the limits of play on a particular field.He learned the hard way about a Wrigley Field ground rule....
- By establishing ground rules, the playing field can be leveled for all participants.
- Under the ground rules of the Astrodome, the ball was in play.
- multilaminate
- multilaminated
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- multilanguage
- multilateral
- multilateralisation
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- multilateralism
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- multi-length
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- multilineality
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- multilingual
- multilingualism