What is the 4th dimension?
While no scientific theory is ever (or should be) closed to
controversy, the answer currently accepted by most Physicists
(thanks to Einstein) is that the fourth dimension is time, or that
time is the way we experience the fourth dimension.
It depends on your concept of what exactly is a dimension.
Initially dimension, as a concept, was determined by a measured
displacement or finite movement. Typically one experiences going
from Point A to Point B, as a change in placement. As one travels,
some x amount of distance has been covered, the same is true of
time, as it has passed as the distance was traveled. Typically in
math the number of dimensions available, is only limited by your
computer and you imagination. But I digress, dimensions are about
how many perpendicular lines can cross at any one Point. Volume and
space are words that describe 3D type dimensional concepts. The 'D'
in 3D stands for 'dimension'. We all know up and down, left and
right, and forward and reverse. So then, what else is there, in a
linear displacement type distance environment?
The definition : hyper- pref. 1. Over; above; beyond:
hypercharge. 2. Excessive; excessively; relates more to your
question, and in terms of Extension that Creates Dimension,
'Hyperspace' is a more correct Label for the 4th dimension.
In Hyperspace, one can have four lines intersect at one point,
each perpendicular to the others.