In legal terminology, a person who is beneficiary of a trust; the one who enjoys the benefits of property held in trust.
From Old French cestui, from Latin cis (this) + the pronoun suffix -tui. The term appears in Norman legal language brought to England after 1066.
Legal English is full of French words like this because William the Conqueror brought Norman French to England—and 'cestui' is one of the oldest surviving Norman French legal terms still used in courts today!
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