A boy or man who typifies or is the perfect example of a particular characteristic, attitude, opinion, cause, or type of person. Pete managed to disassemble their washing machine, fix the problem, and then reassemble it all by himself? Wow, he's like the poster boy of DIY. What new earth-saving plan does the poster boy for environmentalism have in mind now? Mr. Walsh built his fortune from nothing, through his own tireless work and intense ambition. He really is the poster boy for the rags-to-riches American Dream.