It is very easy to get our terms mixed up when they are used interchangeably with one another. Sometimes, however, using terms as if they are interchangeable is inappropriate, as such terms do not mean the same thing. When terms are used as if they are interchangeable, but inappropriately, all this serves to do is cause more confusion. Hence, it is important to define your terms before using them, lest you end up speaking, writing, and engaging in the world in a confused manner.
There are many terms that get mixed up in this manner. However, there are three terms that get used interchangeably in an inappropriate manner that we’ll be discussing here. These terms are open relationships, polyamory, and a triad. It is quite often the case that these three words are used as if they all mean the exact same thing. While these words refer to very similar sorts of relationships --namely, relationships that are non-monogamous (i.e. involving more than two parties)-- these words do not mean the same thing. Indeed, when you get down into the particulars, these terms actually mean very different things.
Open relationships are essentially where you have one primary partner who you have a romantic and emotional commitment to, but where both parties have sexual desires outside of that commitment. In open relationships, it is agreed that both parties can peruse such desires outside of their relationship. Essentially, open relationships are for people who are looking for more sex out of their lives, not necessarily more love.
Polyamory, on the other hand, is a bit different. Polyamory is when you have many different romantic and emotional commitments. The ordinary idea of monogamy is to be committed, intimate, and emotionally tied towards one person. With polyamory, this expands out towards multiple people. Contrast this with open relationships, where, in open relationships romance is not the reason for seeking out other partners: rather, sex is the reason.
One thing that is distinct about both polyamory and open relationships is that not all of the partners mingle with one another. Generally, each partner has individual relationships with multiple people. For example, say you are in a polyamorous relationship and you have multiple other partners outside of your primary partner. Generally speaking, these multiple partners are not going to be romantically involved with your primary partner.
Finally, we have the triad. A triad is when three people are in a relationship with one another, and romantic commitment is shared between all three partners. Many triads actually spring forth from monogamous relationships, whereby a couple finds a third person that they are both interested in joining the relationship. This is different from a relationship where there is two partners, and one of them is involved with another person. Rather, a triad is when three people are actively involved with one another. This doesn’t have to be just three people, however. There is also the quad, in which four people have the same relationship dynamic as a triad. It is quite possible for the number of participants in such a relationship to grow in numbers --though it is difficult to say the cap for this.
After the enumeration of these terms, it is quite clear that many simply say “open relationship” or “polyamory” to refer to all of these types of relationships. This, however, is an inaccurate way of communicating. Making these distinctions is crucial in remedying the stigma attached to non-monogamous relationships. Much of the stigma derives from the confusion surrounding terminology, which allows the uninformed to make broad-brush statements about non-monogamy. The less confused people are about terms, the easier it will be for the stigma surrounding non-monogamy to be broken.