Multiqueer is a descriptor of one's queer experience as multiple. As in, someone can experience queerness in various ways. For example, one may experience both a queer gender and a queer sexual orientation. This may also mean one's experience with queerness is vast or fluid, such as in the case of genderfluidity or abrosexuality. One may also hoard labels, or use several queer labels to describe their identity.
History and Flag
Tumblr user the-gender-collector-emself proposed several flags for the identity on September 20, 2020, in response to an anonymous user. The label itself is of uncertain origin, but has been used since at least 2009, with the earliest known use being in the book "The Story of Sexual Identity: Narrative Perspectives on the Gay and Lesbian Life Course" by Phillip L. Hammack.