Nope.

     Oh, you wanted a longer answer.  Okay.  According to the OED,
     cheating means "fraud, deceit, swindling."  There's a nice quote
     from 1532: "The first...ground of Chetinge is...a studdy to seme
     to be, and not to be in deede."  In other words, cheating is to
     convey through deliberate action the impression that one is of a
     particular nature while one is, in fact, something quite
     different. What this boils down to with polyamory is that
     polyamorous people do not tell partners, lovers, or prospective
     members of those groups that they are monogamous when in fact
     they are not -- nor do they allow these people to assume they are
     monogamous, regardless of how convenient or personally
     advantageous such assumptions might be.  The words "honest",
     "negotiate", "communication" and "being out" occur frequently in
     discussions of how polyamory usually works.

     As Stef puts it: 

     "I think the key in defining polyamory is *openness*, that is,
     having multiple relationships with the knowledge and consent of
     your partner(s) rather than by deceit.  (How much openness, how
     many details are shared, of course varies widely.)  A great many
     people have secret affairs while they're in a supposedly
     monogamous relationship. I think those people might have the
     potential to be polyamorous, but I do not think they are
     practicing polyamory.  Another key in defining polyamory, IMO, is
     that it need not involve sex (although it often does)."

     Generally speaking, if someone openly practices "more than one
     love" and calls themself polyamorous, they probably are; if they
     practice "more than one love" and call themself monogamous, do
     not adjust your television: the problem is *not* in your
     receiver.