Definition: Dek is a journalism slang term for the summary that appears below the headline of a story. Dek is a term often used by editors when they're referring to stories they're working on. In other words, your editor might tell you that your dek needs to be reworked.
Dek, like other slang terms editors and copy editors use, is a word you might hear spoken or written on a story, during the editing process, but you would not see it appear in a proper sentence.
Also Known As: Sub Hed (sub heading); Slug