Possessing all three

spatial dimensions:

height,

width, and

depth. A

sphere, a

cube, and a

pyramid are all simple

geometric three-dimensional figures. When contrasted with a

four-dimensional object, a three-dimensional object does not change with

time.

In a literary context, a three-dimensional character is one possessing ambitions, motives for those ambitions, and a clear history to explain those motives. Three-dimensional are the most believeable kind and take the most time to write, which is why your average writer will settle for the two-dimensional sort.