means Existing in effect or essence but not in actual physical form — either as a near-equivalent of the real thing or as something simulated by computers.

from From Latin 'virtus' (strength, virtue, power), via medieval Latin 'virtualis,' which described something possessing the inherent power or effect of a thing without being that thing in substance. For centuries 'virtual' meant 'in effect, for all practical purposes' — a virtual victory, a virtual stranger. Its modern computing sense (virtual memory, virtual reality) blossomed in the mid-20th century, taking that old 'real in effect, not in fact' meaning and aiming it squarely at machines.