Meaning of third dimension

third' dimen'sion

Pronunciation: [key]
  1. the additional dimension by which a solid object is distinguished from a planar projection of itself or from any planar object.
  2. something that heightens the reality, vividness, or significance of a factual account, sequence of happenings, etc.: The illustrations added a third dimension to the story.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.