Polyamory itself is under the umbrella of consensual non monogamy. Consensual non monogamy involves people who have multiple sexual and/or loving relationships with the knowledge and enthusiastic consent of all involved.
I think a polyamorous individual is one who is able and desires to manage multiple romantic relationships at the same time.
Polyamory as a relationship style is where a person is open to developing multiple loving relationships at the same time. They may not currently be in multiple, loving relationships but there is the potential for them to develop a relationship of that level of commitment and intimacy if the chance arises.
People who are not open to having more than one loving relationship and wish to restrict the emotional and/or romantic commitment outside a primary relationship are not polyamorous, because they aren't open to maintaining multiple loving relationships. Some swinger, for example, set these rigid boundaries.
But you don't get to say what relationships are loving, or who is or isn't open to multiple loving relationships unless you are in those relationships. If someone self identifies to restricting themselves to one "proper" relationship but will have sex with others, sure, say that doesn't fit the poly definition of multiple loving relationships. But if someone practicing solo poly tells you that they have a number of partners, some sexual, some loving, some both, all separate, you don't get to say that isn't polyamory because it doesn't reflect the traditional relationship model where you believe true love can only exist.