tantamount - TANT-uh-MOUNT - the same as, identical
Example: "North Korea has announced that South Korea's joining with the world powers against the recent missile testings as tantamount to a declaration of war with North Korea."
As a starter: and as a former teacher in English, I hope to add to reader's vocabulary by presenting a word a day in simple terms that anyone can understand - from current use in publications, radio,TV, etc. Remember: use a new word three times in a day and it's yours forever!