Superlative form of mighty: most mighty.(adjective)
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Use "mightiest" in a sentence
"On June 5, 1950, the U.S. Supreme Court struck what was called the mightiest blow for freedom and full citizenship for African-Americans since the Civil War."
"With justice England is called the mightiest naval power in the world."
"One of their mightiest was a very old apparatus, one that had been forgotten for countless ages."