[JadeNB]

> How does one formally define a spinor? I've seen the definition of a spinor field as "things that transform like a spinor", and a spinor as a "representation of the spin group" (which representation), but I would like to know a canonical mathsy definition of what the heck a "spinor" is! May I please have one? :)

For Spin(8), three of the four fundamental representations are conjugate, and so we can use any one of them to define spinors.