Source : Webster's Revised Unabridged Dictionary (1913)

Uppermost \Up"per*most`\, 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.

Source : WordNet®

uppermost
     adj : at or nearest to the top; "the uppermost book in the pile";
           "on the topmost step" [syn: {topmost}, {upmost}]
     adv 1: in or into the most prominent position, as in the mind; "say
            what comes uppermost"
     2: in or into the highest position; "the blade turned
        uppermost"