Since there are lots of different ways to organize (or not
     organize, if one is blessed by the Goddess of Chaos, or has a
     taste for happy anarchy, or is a principled egalitarian)
     relationships, it follows that there are ways of describing these
     various arrangements.  This polyjargon has evolved in the
     newsgroup over time, and the words are merely descriptives.  No
     approval or disapproval of any particular arrangement is to be
     expressed or implied.

     Primary - word often used in a hierarchal multi-person
     relationship to denote the person with whom one is most strongly
     bonded.  In some cases this bond or commitment takes the form of
     legal marriage.  As bigamy is not legal, the option of having two
     (or more) legally wedded primaries simultaneously is not
     currently practicable, though non-legal ceremonies may certainly
     be performed.  In some cases "primary" refers to the lover with
     the most seniority.

     Secondary - follows from primary, in a hierarchal relationship,
     denotes a person with whom one is involved without the emotional,
     legal, or economic complexities and commitments of primary
     bonding.

     Yes, some people talk about tertiaries and so on.  Some people
     also don't like the terms primaries and secondaries or the
     concepts behind the terms, preferring to have "a circle of
     equals" as one poly person called it.  Stef contributed the term
     "Non-hierarchical Polyamory" for this kind of arrangement.

     Triads - three people involved in some way.  Often used in a
     fairly committed sense, in some cases involving ceremonies of
     commitment, but also used simply to mean "three people who are
     connected".  Example: "Jodine, Mischa and Mickey are a FMM triad
     living in Excelsior."

     Vee - Three people, where the structure puts one person at the
     bottom, or "hinge" of the vee, also called the pivot point. In a
     vee, the arm partners are not as commonly close to each other as
     each is to the pivot.

     Triangle (or equilateral triangle) - relationship where three
     people are each involved with both of the others.  Sometimes also
     called a triad.

     Line Marriage - term from the works of Robert A. Heinlein,
     science fiction writer, meaning a marriage that from time to time
     adds younger members, eventually establishing an equilibrium
     population (spouses dying off at the same rate as new ones are
     added).  This is a different form of familial immortality than
     the traditional one of successive generations of children.
     (Definition courtesy of M. Schafer, and yes, there are people who
     are in situations like this who use the term to describe their
     family.)

     Polyfidelity: Relationship involving more than two people who
     have made a commitment to keep the sexual activity within the
     group and not have outside partners.  (Rumor has it that this
     term was coined by the group Kerista.)

     Quads, pentacles, sextets and more: There are polyfolk who exist
     in multiple arrangements with more than three members.  Geometry
     can get complicated, and creative nomenclature abounds. As in
     every other aspect of polyamory, the precise bonds of intimacy
     vary from group to group and from member to member within groups.