Einstein named his theory "special relativity" to distinguish it from his later theory, the "general theory of relativity." The term "special" in "special relativity" refers to the fact that it deals with a specific class of reference frames, namely inertial frames, which are frames of reference that are either at rest or moving with a constant velocity relative to each other.
In special relativity, Einstein introduced the concept that the laws of physics should be the same in all inertial frames of reference. This means that the fundamental principles governing the behavior of physical phenomena, such as the speed of light, remain consistent regardless of how fast an observer is moving relative to the source of light.
The term "relativity" in special relativity highlights the central idea that the laws of physics should be relative or invariant under certain transformations between different inertial frames. In other words, the physical laws and phenomena should appear the same to observers in different inertial frames, even though their measurements and observations may differ due to the effects of time dilation, length contraction, and relativistic velocities.
While special relativity does introduce some counterintuitive concepts, such as time dilation and the relativity of simultaneity, it was named "special" to emphasize its focus on a specific class of reference frames and the relative nature of physical laws within those frames. The "absurdity" or seemingly paradoxical aspects arise when one attempts to apply classical Newtonian intuition to situations involving high speeds or relativistic effects, but they are consequences of the theory's profound implications rather than inherent contradictions within the theory itself.