1 definition by Slumdog23
A term referring to a woman whose appearance can range from really good looking to downright ugly. As a result, males cannot categorize such a female on a scale of 1-10 as her ranking is incredibly volatile. Thus, their attractiveness is simplified to a different scale for this rare category of women which is marked by a +1 for looking good at the time or -1 for looking bad on an occasion, hence the term ion.
Damn that girl is such an ion, yesterday I would've banged her for sure but today she looks like snooki's asshole.
by Slumdog23 October 27, 2010