Turns out, paramount doesn’t have that much to do with mountains. It does, however, describe something that’s of highest importance. Tantamount, on the other hand, refers to something that’s equal to something else. While the two words sound similar, that’s really all they have in common.
Paramount
Paramount is an adjective meaning “of utmost importance.” It can also describe someone with the highest level of power or jurisdiction, like a ruler. Paramount can also be used as a noun, where it describes a ruler with supreme power.
Tantamount
Tantamount means equal. It’s only ever used as an adjective, and is almost always followed by the preposition to, as in “This is tantamount to that.”
Common Uses and Synonyms
Neither paramount nor tantamount are words that tend to come up in everyday speech or writing. Depending on the context, using these words can sound educated, or they might sound pretentious.
Both words tend to be used by attorneys in courtrooms. For example, a lawyer might complain to a judge about a witness’s lack of cooperation by saying “His evasion of my last question is tantamount to perjury.” Here the attorney is equating the witness’s evasion with the crime of perjury (lying under oath).
By saying something like “The facts are paramount in this case,” an attorney reminds the judge and jury that listening to the facts is of utmost importance.
In casual conversation, it’s best to use less formal synonyms in place of paramount and tantamount. Instead of saying that “A is tantamount to B,” you could just say that “A is equal to B,” or that the two items are alike. Rather than declaring something the paramount item on your agenda, you can just call it the main item, or the most important item.