Of the greatest degree (9)
(Other definitions for uttermost that I've seen before include "Extreme" , "Last" , "Maximum - extremity" , "best" , "at the furthest limit" .)
(Other definitions for utmost that I've seen before include "last" , "Furthest point or degree of effort" , "At furthest limit" , "Furthest - greatest possible" , "Furthest or extreme" .)