Virtual meaning

not physically existing as such but made by software to appear to do so.

Video or online presence without being computerized 

OPTICS

relating to the points at which rays would meet if produced backwards.

MECHANICS

relating to or denoting infinitesimal displacements of a point in a system.

PHYSICS

denoting particles or interactions with extremely short lifetimes and (owing to the uncertainty principle) indefinitely great energies, postulated as intermediates in some processes.