Also connective. An expression that provides an argument with its logical form. Constants cannot vary without varying the form of the argument.
A constant with a value of either true or false (or T or F).
A constant that can have one of two values: true or false. The form of these values in Fortran is: .TRUE. and .FALSE. respectively.
A constant that specifies the value .TRUE. or .FALSE..
In symbolic logic, a logical constant is a symbol that has the same semantic value in all models. Two important types of logical constants are logical connectives and quantifiers. The equality predicate (usually written '=') is also treated as a logical constant in many systems of logic.