1. [common] Variety, type, kind. “DDT commands come in two flavors.” “These lights come in two flavors, big red ones and small green ones.” “Linux is a flavor of Unix” See vanilla.
2. The attribute that causes something to be flavorful. Usually used in the phrase “yields additional flavor”. “This convention yields additional flavor by allowing one to print text either right-side-up or upside-down.” See vanilla. This usage was certainly reinforced by the terminology of quantum chromodynamics, in which quarks (the constituents of, e.g., protons) come in six flavors (up, down, strange, charm, top, bottom) and three colors (red, blue, green) — however, hackish use of flavor at MIT predated QCD.
3. The term for class (in the object-oriented sense) in the LISP Machine Flavors system. Though the Flavors design has been superseded (notably by the Common LISP CLOS facility), the term flavor is still used as a general synonym for class by some LISP hackers.