The term FRAT HOUSE LETTER is composed of five Greek letters commonly used in fraternities and sororities. The letters are PHI (3 letters), SIGMA (5 letters), RHO (3 letters), IOTA (4 letters), and TAU (3 letters). PHI, SIGMA, RHO, IOTA, and TAU are all Greek letters that are used to represent various concepts in fraternities and sororities. They are often used as symbols of brotherhood and sisterhood, and are also used to represent the values and ideals of the organization.