Words one should never use in a formal paper.

[Katleene-chan]

Words people should not use in a paper.

Contractions.
A lot
Alot (this is not a word.)  

[chrystalclear]

Most slang.  

[Orange Noise]

I tend to write using slang, and am rarely ever penalized for it. Kinda seems like a contradiction, but I don't mind so much.  

[Maquarrie]

First person speech and the words there in.

Of course, this is broken if the paper is about oneself.  

[Keren]

Also, in addition to slang, no informal words/sentences.  

[Litia_Echo]

Along with the "alot" there is "atleast" instead of at least. Those are the two I always get me in formal papers.  

[Katleene-chan]

Coma Slices. I know this is not a word, but it is a common grammar mistake.  

[Ame Yuki Kaze]

aint
ya'll
gonna
gotta
kinda
no sir'ee bob  

[Gindy Ann]

Using "and" in a sentence more than once is pretty bad. "And then thins and then and then..." I mean, either use a comma or start a new sentence.  

[stuntmonkey]

Using words like things, kids, or anybody. Be more elaborate about what you are talking about.  

[Rukoric]

Here are two words that shouldn't be used outside of dialogue(because they are not words).

Awhile.

Ahold.  

[agny-pantsu]

Formal papers are EVIIIIIL!!! scream They annoy me, I do not mind using contractions but alot is one of my favourite words and using first person is essential every once in a while.  

[LadyRogue]

One word that I used way too much (I know because my professors got on me about it) was 'basically'. The way I used it was just as a kind of filler, and really didn't add anything to the paper. Of course, this could be just me.  

[Red-Chocolate]

Don't use "stuff". Actually, I got a four on FCAT and I made up most of the adjective, like brain-oodling. Unless that is a word I am unaware of. mrgreen  

[dark_elf]

Swearing, extrem slag, words and pharse that only you, or those around you, understand. Like... "The sky was Dusty's eye blue." Only my family would understand that. (just so you guys know, Dusty is one of our cats and he has very blue eyes ^-^)