Know-it-all
（重定向自Besserwisser）
A know-it-all or know-all is a person who obnoxiously purports an expansive comprehension of a topic and/or situation when in reality, his/her comprehension is inaccurate or limited. This display may or may not be directly expressed.
The German word Besserwisser is also used in some languages, literally meaning "better knower."