What is "whiffenpoof"

The word whiffenpoof can refer to:

• an imaginary or indefinite animal; e.g. "the great-horned whiffenpoof;"
• a device used for tracking exercises;
• the Whiffenpoof Fish that forms the subject of a piece of comic dialogue in Victor Herbert's 1908 operetta, Little Nemo;
• The Whiffenpoofs, the Yale University singing group, founded in 1909 and named after the imaginary beast in the operetta;
• a stereotypic Yale alumnus or Ivy Leaguer