What's the word for “someone that doesn't know something but pretends to know it?” [closed]

Question

This guy thinks a person is arrogant when he knows nothing about that person and just telling everyone about how arrogant that guy is. So what is the term for this kind of person?

Answer 1

swank

behavior, talk, or display intended to impress others.

posture

behave in a way that is intended to impress or mislead others.

pretentious

attempting to impress by affecting greater importance, talent, culture, etc., than is actually possessed.

know-it-all

a person who behaves as if they know everything.

smart-aleck (ass)

irritating as a result of behaving as if one knows everything.

Answer 2

Perhaps a bloviator? Oxford Online defines bloviate as

Talk at length, especially in an inflated or empty way.

Similarly, windbag

A person who talks at length but says little of value.

Oxford Dictionaries Online

Also gasbag

One given to empty or boastful talk.

American Heritage

Answer 3

Sarcastically, Mr.Know-it-all.
informally, Smarty pants. Reference : marriam-webster

Answer 4

An idiom that comes very close to meaning what you want to convey is empty vessel, from the adage "Empty vessels make the most noise". The literal meaning is that those least endowed with knowledge or wisdom are those who talk the most.

Answer 5

bigmouth

: a person who freely announces personal opinions and judgments; know-it-all, smart-ass The Dictionary of American Slang

Answer 6

I would say this person sounds jealous.

4. Troubled by the belief, suspicion, or fear that the good which one desires to gain or keep for oneself has been or may be diverted to another; resentful towards another on account of known or suspected rivalry:

b. in respect of success or advantage: Apprehensive of losing some desired benefit through the rivalry of another; feeling ill-will towards another on account of some advantage or superiority which he possesses or may possess; grudging, envious. Const. of (the person, or the advantage).