"Consciousness" seems pretty obvious. The ability to experience qualia. I do it, you do it, my dog does it. I suspect all mammals do it, and I suspect birds do too. There is no evidence any computer program does anything like it.
The definition of "featherless biped" might have more practical merit, because you can at least check for feathers and count limbs touching the ground in a mostly reliable fashion.
We have no way to "check for qualia" at all. For all we know, an ECU in a year 2002 Toyota Hilux has it, but 10% of all humans don't.
It's "intelligence" I can't define.