Dictionary Definition :
Definition[1]
:
The three things possible and impossible to a Buddha. He can (a) have perfect knowledge of all things; (b) know all the natures of all beings, and fathom the affairs of countless ages; (c) save countless beings. But he cannot (a) annihilate causality, i.e. karma; (b) save unconditionally; (c) end the realm of the living.
Source
:
A Dictionary of Chinese Buddhist Terms, William Edward Soothill and Lewis Hodous