Final answer:
An annulment is the legal term indicating a marriage was never valid, signifying that the marriage is treated as if it never existed.
Step-by-step explanation:
The legal term that indicates a marriage was never valid is an annulment. An annulment is a legal decree that a marriage is null and void, in contrast to a divorce, which ends a legally recognized marriage. An annulled marriage is considered invalid from the start, as if it never existed. Factors that can lead to an annulment include marriages entered into because of fraud, coercion, or where the parties lack the capacity to consent, such as cases of mental incapacity or underage individuals without proper consent from guardians or the court.
Historical instances provide insight into the complexity of marriage legality, for example, King Henry VIII's desire to annul his marriage to Catherine of Aragon, as he believed his marriage was never legitimate according to Catholic Church law. In modern contexts, the legal struggles surrounding the recognition of same-sex marriages also show how the validity and rights associated with marriage can vary greatly and have profound impacts on the lives of individuals.