According to Merriam-Webster, "ratify" means to make a formal approval or official sanction. "All attending member nations agreed to ratify the proposed treaty" is an example of how to use the transitive verb "ratify" in a sentence.
Certify, consent, sanction, endorse and approve are examples of synonyms for the word "ratify," according to Roget's Thesaurus. Deny, disallow, oppose, refuse and renounce are examples of antonyms of the term "ratify." The word's usage dates back to the 14th century and is associated with political, legal and bureaucratic domains. For instance, students of American History learn that amendments to the Constitution are ratified before they become law.