What does "identical" mean?

Identical: Uttering sameness or the same truth; expressing in the predicate what is given, or obviously implied, in the subject; tautological. When you say body is solid, I say that you make an identical proposition, because it is impossible to have the idea of body without that of solidity. Fleming. Identical equation (Alg.), an equation which is true for all values of the algebraic symbols which enter into it.