1. letterhack - Noun
2. letterhack - Verb
letterhack (plural letterhacks)
(dated, fandom slang) A fan who is a prolific writer of letters to periodicals.
letterhack (third-person singular simple present letterhacks, present participle letterhacking, simple past and past participle letterhacked)
(dated, fandom slang) To write letters to periodicals very frequently.