[Abbr. for Volt-ampere] - A Volt-Ampere (also volt-amp) is the basic unit of apparent electrical power. The value is derived by multiplying the voltage applied to a device (V) by the value of the current consumed by the device (A). See also Watt.
[Abbr. for ventilation and air conditioning] - VAC systems are all those components used in air-conditioning and ventilation technology (which serves to condition guided air currents). VAC technology is distinct from process-air technology.
In classical physics, a vacuum is defined as space which contains no matter whatsoever. Electromagnetic waves can propagate unimpeded in a vacuum.
The opposite of generative propagation, vegetative propagation describes asexual reproduction in biology.
Viruses are particles or information carriers dependent for survival upon the metabolism of a host cell, since they themselves have no cytoplasm and are incapable of metabolism. Viruses are thus de facto not living organisms.