Oulip is the word used to describe something written without using a certain letter of the alphabet
Examples include Ernest Wright's "Gadsby" and Georges Perec's "A Void".
The name is derived from the organisation of writers known as OuLiPo (Ouvroir de la Littérature Potentielle, or the "Workshop for Potential Literature")
Writings from the organisation are characterised by generative devices, consisting of either constraint-based (eg. not using a particular letter of the alphabet) or rule-based writing.
sources: http://www.snpp.com, http://www.growndodo.com/wordplay/oulipo/