Аннотация:The paper contributes to the important and urgent problem to extend the physical theory of space-time in a Finsler-type way under the assumption that the isotropy of space is violated by a single geometrically distinguished spatial direction which destroys the pseudo-Euclidean geometric nature of the relativistic metric and space. It proves possible to retain the fundamental geometrical property that the indicatrix should be of the constant curvature. Similar property appears to hold in the three-dimensional section space. The last property was the characteristic of three-dimensional positive-definite Finsleroid space proposed and developed in the previous work, so that the present paper lifts that space to the four-dimensional relativistic level. The respective pseudo-Finsleroid metric function is indicated. Numerous significant tensorial and geometrical consequences have been elucidated.