Which of the following is defined as equivalent or having the same meaning?

The term "tantamount" is defined as equivalent or having the same meaning. This word conveys the idea of one thing being equal in value, significance, or effect to another. In many contexts, "tantamount" is used to indicate that two different situations, actions, or entities produce the same outcome or bear similar weight in terms of importance.

The other terms provided do not align with this definition: "analogous" refers to a similarity between things but doesn't imply they are identical or equivalent in meaning; "dissimilar" indicates a difference and thus is the opposite of equivalent; "identity" pertains to sameness or uniqueness rather than equivalence in meaning. Therefore, the use of "tantamount" is the most accurate choice when describing something that is equivalent.