A “plurid”, short for “plural identity”, is something as or with which the system collectively identify and/or that affects identity throughout the system in a way that affects how the system present themselves.
A plurid can be a collective identity such as being gay, dogkin, or disabled. This might be an identity that is very common among individual members, that is ascribed to the system's singletsona/that they present as, that they have lived experiences or a social circle associated with, or that no individual member has but that they feel they make up collectively. However, something can be a collective identity for any reason.
A plurid can also be something that isn't necessarily an identity itself but that can affect identity, such as love, outer space, or books. While these things have identities associated with them (e.g. lovegender, spacekin, writer), they are not themselves actually identities.
These are called xenoplurids, although it is not important when coining a plurid to denote if it is a xenoplurid or not, and there can be gray areas or in-system disagreements. The counterpart to "xenoplurid" is "oikoplurid". However, if the coiner prefers to call it something else, this is also acceptable
A system can use "[thing]plurid" as a label, or they can say "[thing] is our plurid".
This post is a self-recoin. The original coining post for plurid can be found here, and while the thing it describes is still a form of plurid, the original definition is narrower than how it is now defined.
The difference between the old version of plurid and the current version is that the old version of plurid only covered things that "typically" constitute identities (e.g. genders, kintypes, orientations, etc.) whereas the recoined version of plurid includes things that affect identity in ways outside of being the identity itself.
[This post has no DNI other than not to involve it in discourse, mockery, or other harassment]