When combined into the term is generally used as a noun to describe a person who is perceived as being overly obsessed with adult content, or more broadly, as a derogatory label for someone seen as a "loser" or a "degenerate" due to their online habits. Linguistic Context and Usage
"I'm trying to clear my head before I make a bad decision, time for a quick fapnut." 3. Content Categorization (Adjective) fapnut.