Tautology
A tautology is a statement form that is always true, regardless of the truth values of the individual statements substituted for its statement variables. A statement whose form is a tautology is a tautological statement. (Can be interpreted as “TRUE”)
Contradiction
A contradiction is a statement form that is always false, regardless of the truth values of the individual statements substituted for its statement variables. A statement whole form is a contradiction is a contradictory statement. (Can be interpreted as “FALSE”)