Virtual meaning : A virtual member function of a class. In effect or essence, if not in fact or reality; imitated, simulated. Having the power of acting or of invisible efficacy without the agency of the material or measurable part; potential. Nearly, almost. (A relatively recent development in meaning) Simulated in a computer or online. Operating by computer or in cyberspace; not physically present. (of a class member) Capable of being overridden with a different implementation in a subclass. Pertaining to particles in temporary existence due to the Heisenberg uncertainty principle.