From Longman Dictionary of Contemporary Englishvexvex /veks/ verb [transitive] old-fashioned to make someone feel annoyed or worried —vexing adjective a vexing problem→ See Verb table
Examples from the Corpus
vex• The problem was considered particularly vexing because, as the research of contemporaries showed, it affected middle class women most.• The nature of its relationship to the poor is perhaps the most vexing ethical issue that Holy Trinity faces.• But rendering attention to these vexing questions is prudent and the right thing to do.Origin vex (1400-1500) Old French vexer, from Latin vexare 