Definition of "deco"

deco¹

noun
uncountable
1. (underwater diving, informal) Decompression.

deco²

noun
plural decos
1. A friendship book in which people add decorative elements such as drawings, stickers and sequins.
  Quotations
  Start your own Traveling Deco Journal […] Improve your Deco and Friendship Book Bindings
  2004, Tamara Stevens, What Is Snail Mail - The Lost Art of Letterwriting, page 110
  […] little booklet called the 'deco' (decorated friendship book), passes from person to person through the mail in an envelope with each recipient decorating a page including their name and address before passing it on.
  2005, Amy Spencer, DIY: The Rise of Lo-fi Culture, page 131
  Regular friendship books had a variety of variations, such as slams, crams, and decos.
  2017, Mark Duffett, Fan Identities and Practices in Context: Dedicated to Music, page 194