Webster’s Revised Unabridged Dictionary · 1913 Uppermost Up′per·most′ (ŭp′pẽr·mōst′), a. [From Up, Upper; formed like aftermost. Cf. Upmost.] Highest in place, position, rank, power, or the like; upmost; supreme. Whatever faction happens to be uppermost. Swift. ‹ Upper Uppertendom ›