1. A term used to describe the shipping or romantic involvement of Pokemon's Jessie and James, usually in fanfiction or fanart and the community that produces it.
It is typically used to describe fantasy stories and other works of art focused around this shipping, but can also be applied to the belief or hope that they will become a couple and, sometimes, the characters' current relationship in the anime, depending on how it is perceived by the viewer.
2. A shorthand spelling for "Jessie And James Love".
Oh my God, I just realised I've written over 25 JAJL fanfics! I can't help it, it's just too freaking cute!!