• Answer is : Operator

    Predicate Is an expression that evaluates to TRUE, FALSE, or UNKNOWN. Predicates are used in the search condition of WHERE clauses and HAVING clauses, the join conditions of FROM clauses, and other constructs where a Boolean value is required.

    IN is the logical operator

    Please visit the below one to know all the logical operator

    http://msdn.microsoft.com/en-us/library/ms189773.aspx