a kirby, but without it's nublies (matpat's term for hands) and without any feet. thus, it is just an orb a thus an orby.
however, i could also be used to refer to a completely amputated person if you're a disrespectful retard.
person 1: did you see that guy?
person 2: yeah, he's an orby.
person 1: *slaps the shit out of person 2* that's disrespectful.
person 2: ouch