I'm looking for the opposite word to "indent." Is it "outdent", or is it "unindent"?
Corresponding to "Tab" and "Shift Tab" in most editors.
In that case you'll want unindent, as it reverses the indent action, and as outdent refers to a (usually left-) hanging block of text.
The opposite of indent is outdent, according to Christopher Hoot, graduate of Yale University and graphic design instructor at the University of Akron.
Outdent is modelled on indent, replacing in with its opposite, out.
It refers to multident -> multiple “dents” in a paragraph.
Verb outdent is to indent negatively, bring towards the margin.
You can also use de-indent.
Dedent or corrupted Outdent is correct. http://en.wiktionary.org/wiki/dedent
(Disclaimer: The following is "from what I know")
Latin in- (alt. im-) is a prefix, not to be confused with the english word in (which is just shorthand for inside/inward/within). But we do commonly confuse the two, which is why Outdent is a valid word.
The prefix in-, when used with verbs, signifies "what is being done unto" rather than "what we do". (i.e. the object's perspective, figuratively "from itself/within", which is probably why people confuse the two words).
When used with a noun or adjective, in- is typically a negator or declaration of absence (unless it's a verbal noun/adjective, in which case the verb dictates the meaning). This is similar to how the - sign in math is used to describe a negative number (i.e. inactive/inaction "not active/acting" or implosive/imposing "negatively explosive/exposing", which showcases another reason why we mistake in for in-, because an implosion is effectively an "inwards explosion").
Here it becomes even more confusing, because we often use latin verbs as nouns and adjectives (because the english syntax, and thus vocabulary, is different from the latin one). So while the noun for the verb import should, for instance, be importation or importment, we just say "an import" or "something imported" instead. Neither importation or importment are correct english words, afaik.
I.e. indent means "to have toothed into", whereas noun dent means "tooth" and verb edent means "to tooth into". However, edent is not a valid english word because indent or dent is used instead. Because, you know, reasons... "To tooth" is a figurative way of saying to strike, blow, or sink into.
In other words, indent isn't even a noun, but a verb that we sometimes use as a noun. The correct noun of indent, in english, is indentation or indentment. There's no such thing as "an indent".
Another way to explain the logic is that you cannot technically dent something "the other way" because a dent is still a dent, and it's either there or it's not. Running is similar - you can change your direction, but you'll still be running.
Other words: Invent/event, invoke/evoke, Inject/eject, Involve/evolve http://en.wikipedia.org/wiki/List_of_Latin_words_with_English_derivatives