Future passive participle of mergō mergendus (feminine mergenda, neuter <span class="searchmatch">mergendum</span>); first/second-declension participle which is to be swallowed up, plunged...
mersūrum fuisse — — — verbal nouns gerund supine genitive dative accusative ablative accusative ablative mergendī mergendō <span class="searchmatch">mergendum</span> mergendō mersum mersū...