Pronounfluid is the act of switching or transitioning between two or more pronoun sets over time. One's pronouns may change over the course of hours, days, weeks or months. The gender of the person does not matter, and does not have to change with the pronouns. Being pronounfluid means that ones preferred pronouns can change regularly or irregularly over time, and this does not directly affect one's gender. For example, a genderfluid person may go by xe/xem one day, and he/him the next, and then a week later, switch back to xe/xem. Their gender may or may not have changed during this time, and it does not matter what their gender changed to. This is similar to one definition of multipronominal, but more specific in the aspect that their gender does not change according to the pronoun switches. Pronounfluid people may be genderfluid (though they do not have to be), but their changing gender does not typically have to correspond with their changing pronouns. This is a form of pronoun non-conforming.
History
The term was coined by fandom user YellowfangWC, who identifies as pronounfluid themself.