peritext

From peri- +‎ text.

peritext (plural peritexts)

1. (literary theory) Images and textual elements which surround, or are secondary to, the main body of a published work, such as an introduction, notes, front covers, etc.
   • 2011, David Bellos, Is That a Fish in Your Ear?, Penguin 2012, p. 143:

     The main work is not the translation at all, but Nabokov's appropriation of it through his inflated peritext.