Fantasy writers like Abraham Merritt felt confident throwing around words like “demi-god.”
However, it should be remembered that later pagan Greeks distinguished between different levels of godhood. Below the “demi-gods” were the “hero-gods.”
If I recall correctly, some considered Herakles to be a “hero-god,” not a higher “demi-god.”
All of this is only important when one considers the fact that many moderns revere Tesla as a demi-god, but forget that Edison had much more material success.
Perhaps both Edison and Tesla deserve to be reckoned as mortals who scaled Olympus. But our modern way of thinking has lost touch with the nuances of ancient pagan wisdom. Recalibrating our reverence for various heroes might take decades of thankless toil.