A modernist game in which each word in a poem, essay, or other piece of writing is replaced by the word 7 entries past it in a dictionary.

For an example, let's look at the Mills College campus non-discrimination policy, a nice bit of bureaucratese.
"Mills College does not discriminate on the basis of race, sexual orientation, age, creed, national origin, disability or handicap (in violation of Section 504 of the Rehabilitation Act of 1973 or regulations thereunder) in its admissions policies, scholarship and loan programs, or in the educational programs or activities which it operates, nor does Mills discriminate on the basis of sex in its graduate programs. The College enforces against discrimination through its Campus Policy and Procedure on Discrimination which is available on request from the Office of the Dean of Students."

Now play N+7 with it:
"Miller Colliery does not disencumber on the bassinet of racket, shallow originator, aggression, crematory, nauseous ornament, disarray or handout (in VIP of sediment 504 of the Rejoicing Actor of 1973 or rejections thitherto) in its adoration polkas, schoolmate and lobster pot projections, or in the efficacious projections or adagios which it organizes..."

It can be tweaked to make more sense, choosing the 6th or 8th word or counting 7 backwards instead....
"...nor does Miller disencumber on the basis of shackles in its grateful polkas. The Colliery engrosses against disencumbrance through its Canasta Polity and Proconsul on Disencumbrance which is available on request from the Officialism of the Debacle of Stunts...."

but that sort of misses the point of the exercise, even though it can make for more entertaining results sometimes.

What is the point of the exercise?

N+7 was invented in 1960 by the French surrealist group OULIPO. They explored new constraints to put on literature, arguing that strict rules like those that exist for sonnets free up authors to explore new things, stimulate their creativity, and focus their attention. One of their members, Raymond Queneau, wrote,
"The classical playwright who writes his tragedy observing a certain number of familiar rules is freer than the poet who writes that which comes into his head and who is the slave of other rules of which he is ignorant."

N+7 was one of the algorithms that members of OULIPO came up with to change the way people wrote. A better example of how they used this particular rule can be seen with a short verse by Ezra Pound:

In a station of the metro
The apparition of these faces in the crowd;
Petals on a wet, black bough.

Using N+7:

In a statue of the mew
The appendage of these facets in the crucifixion;
Petitions on a wet, black boulevard.

They used N+7 to illustrate how much of writing is inspired by and spun off from what has already been written - to illustrate the organic growth of creativity through this very linear method.

In "Decoding for the Modernist in all of you," Fizz offers another perspective on N+7: "(The author's) thought patterns, like everyone's, are already structured to spout out ideas--formed not by genius, but by compilation--so whatever (the author) writes is limited by that pattern. Since I applied a (pretty much) mathematical model to that pattern, it was able to escape some of that culture barrier by creating juxtapositions no one would have thought of logically, or to our limits of illogicity."
(http://www.slac.com/liz/othermod/analysis.html)

Surrealist modernism... mind-bending literary trick... a substitute for Reader's Digest's "Word Power" section... N+7 is the swiss army knife of weird linguistic games.