<span class="searchmatch">fidēiussissem</span> first-person singular pluperfect active subjunctive of fidēiubeō...
fidēiusserit fidēiusserīmus fidēiusserītis fidēiusserint pluperfect <span class="searchmatch">fidēiussissem</span> fidēiussissēs fidēiussisset fidēiussissēmus fidēiussissētis fidēiussissent...