Origin: 1585–95; < MD wijssager prophet, trans. of MHG wīssage, late OHG wīssago, by popular etym. equiv. to wīs wise + sago sayer, from earlier wīzzago wise person; c. OE wītega, akin to wit2
wise guy
–noun
Informal. a cocksure, conceited, and often insolent person; smart aleck: He has a reputation for being a wise guy.
wise·a·cre (wīz'ā'kər) 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 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.]