A formula is valid iff it is true for all models and all variable assignments.
Or, a formula is valid iff it is true in all structures(structure=model, which is a pair(D,J) where D is a discourse and J is a mapping) and all variable assignments.
The following sentences are equivalent.
A formula is valid.
A formula is logically valid.
A formula is universally valid.
A formula is logically true.
A formula is logical truth.
A formula is a tautology.