Abstract
In this article we introduce a new geometric object called hyperbolic Pascal simplex. This new
object is presented by the regular hypercube mosaic in the 4-dimensional hyperbolic space. The
definition of the hyperbolic Pascal simplex, whose hyperfaces are hyperbolic Pascal pyramids and
whose faces are hyperbolic Pascals triangles, is a natural generalization of the definition of the
hyperbolic Pascal triangle and pyramid.We describe the growing of the hyperbolic Pascal simplex
considering the numbers and the values of the elements. Further figures illustrate the stepping
from a level to the next one.