I need a better word for this than "snoutband"

Question

According to dictionary.com:

A snoutband is someone who always interrupts a conversation to correct or contradict the person speaking. Every social group has a snoutband, who thinks they know everything. They probably don't know the meaning of this word, though. At least, not yet.

But nobody uses this word! There has to be a more formal, more appropriate synonym.

Answer 1

I would describe such a person as nitpicky and pedantic.

nitpicky

1. Finicky; overly critical; concerned with insignificant details.

pedantic (comparative more pedantic, superlative most pedantic)

1. Like a pedant, overly concerned with formal rules and trivial points of learning.
2. Being showy of one’s knowledge, often in a boring manner.
3. Being finicky or fastidious, especially with language.

You could use nominal forms and call such a person a nitpicky pedant or pedantic nitpicker. You could forgo one of the words in description, but people should understand what is meant.

Answer 2

who thinks they know everything

In British usage we have know-it-all or Know-all

Answer 3

Buttinsky

: a person given to butting in : a troublesome meddler

there's always some buttinsky who has to tell you there's a better way to do whatever you're doing

"Buttinsky." Merriam-Webster.com. Merriam-Webster, n.d. Web. 3 May 2017.