(A) Someone who likes to hold their superior intelligence over people's heads by correcting them in all the nerdy points, such as grammar.
(B) Someone who's a huge nerd, especially of technology.
(A) "You're such a dousch."
"You spelt 'dousche' wrong. It has an 'E.'"
(B) "In some of my wanderings today, I came across this article on fountain pen ink and discovered that my depth of interest was a strong indicator that I had achieved true powerdork status."