The term DEF___ can be broken down into four distinct parts: MOS (3 letters), ETYM (4 letters), PHAT (4 letters), and FOSHIZZLE (9 letters). MOS stands for Military Occupational Specialty, which is a job classification in the United States Armed Forces. ETYM is an abbreviation for etymology, which is the study of the origin of words and how their meanings have changed over time. PHAT is an acronym for Pretty Hot And Tempting, which is a slang term used to describe something attractive or desirable. Finally, FOSHIZZLE is a made-up word that is used to describe something that is cool, hip, or trendy.