lip·o·gram 
(lĭpə-grăm′, līpə-)
(lĭpə-grăm′, līpə-)n.
A story, poem, or other text in which one or more letters of the alphabet have been deliberately avoided.
[From Greek lipogrammatos, missing a letter : leipein, lip-, to leave, leave out, be missing; see leikw- in the Appendix of Indo-European roots + gramma, grammat-, letter; see GRAMMAR.]