Words that mean the opposite of what they are.

[mr.jp]

Colloquial

Long

[tdn]

Big

Diminutive

[Skammer]

abbreviated

ETA: monosyllabic

[running_coach]

Serpentine.

[Giles]

Non-English

[ultrafilter]

Heterological.

Well, maybe not.

[mr.jp]

invisible

[SciFiSam]

Unwritten.

[california_jobcase]

syllable

[Ludovic]

White

[Svejk_1]

Cromulent

[Superfluous_Parentheses]

incomprehensible

[Ludovic]

infinite

[Enderw24]

@Superfluous_Parentheses

incomprehensible

What?

[Ludovic]

inconceivable

[Superfluous_Parentheses]

@enderw24

@superfluous parentheses

incomprehensible

what?

Incomprehensible!

[SciFiSam]

Miniscule.

[msmith537]

@Ludovic

inconceivable

I don’t think that means what you think it means.

“Wait INflamable means FLAMABLE!!”

-Doctor Nick, The Simpsons

[BellRungBookShut-CandleSnuffed]

abridged

[Invisible_Chimp]

Quotidian