Testimony is "false" if it was untrue when it was given and was then known to be untrue by the witness or person giving it. A statement contained within a document is false if it was untrue when used and was then known to be untrue by the person using it.
Testimony should be viewed in the context of the series of questions asked and answers given, and the words used should be given their common and ordinary meaning unless the context clearly shows that a different meaning was mutually understood by the questioner and the witness.
If a particular question was ambiguous or capable of being understood in two different ways, and that the person truthfully answered one reasonable interpretation of the question under the circumstances presented, then such answer would not be false. Similarly, if the question was clear but the answer was ambiguous, and one reasonable interpretation of the answer would be truthful, then the answer would not be false.