Origin of wiseacrealtered by folk etymology from Middle Dutch wijssegger, altered (infl. by wijs, wise + zeggen, to say) from Old High German wissago, altered (infl. by wis, wise + sago, speaker from sagen, to say) from wizzago, prophet from Germanic an unverified form witag-, knowing: for Indo-European base see wise
Origin of wiseacreAlteration by folk etymology from Middle Dutch wijsseggher soothsayer translation of Middle High German wīssage from Old High German wīssago seer alteration ( influenced by forasago sayer beforehand, prophet ) of wīzago from wīzag knowledgeable ; see weid- in Indo-European roots.
a 1600, from Middle Dutch wijssegger (“soothsayer"), from Old High German wÄ«zzago, from wizzan (“to know")