Abrosexual refers to an individual who's sexuality is changing or fluid. (For example, someone could be gay one day, then be asexual the next, the polysexual the next.) The shift in sexuality might be erratic or regular. While it is possible (and even common) for a person's sexual identity to shift or change in some way throughout their life, an abrosexual person's sexuality may change more frequently, over the course of hours, days, months, or years. Because of this, some abrosexual people may not feel compelled to seek out a relationship.
The timing of the fluctuations is different for every person, for some the fluctuations may be erratic and for others they may be regular. The sexualities that they may fluctuate between also vary from person to person. Some abrosexual people may be fluid between all sexualities, other may be fluid between a few.
The romantic equivalent of abrosexual is abroromantic (or abromantic).
Abrosexuality can sometimes considered part of the asexual spectrum, as an abrosexual person might sometimes be ace-spec, although they might be most commonly allosexual.