untriumphableadj.
Etymology: Previous versions of the OED give the stress as: unˈtriumphable.
society > armed hostility > defeat > [adjective] > not able to be won
1663 S. Butler i. ii. 110 This bloud..Which now y' are bent to throw away In vain, untriumphable fray.
1768 I. 161.
This entry has not yet been fully updated (first published 1926; most recently modified version published online June 2019).