http://dictionary.reference.com/search?q=wiseacre
Wiseacre, n. Slang
A person regarded as being disagreeably egotistical and self-assured.
Alteration by folk etymology from Middle Dutch wijsseggher, soothsayer, translation of Middle High German wissage, from Old High German wissago, seer, alteration (influenced by forasago, sayer beforehand, prophet), of wizago from wizag, knowledgeable.