The word Zakos is defined as the extreme kata side of a 4-dimensional object or space, sometimes incorrectly referred to as the bottom, for the purpose of making the concept clear to the uninitiated. The opposite term is apos.

The words Apos and Zakos were created by Oren Otter for the purpose of having clearly defined terms when discussing 4-dimensional space with aficionados of the topic. They have since become accepted as standard terms.

In the comic Journey to the Bottom of the Multiverse, Tetraspace physicist Steve and his assistant Wilma journey through the realm of Chaos to find the exact Zakos of the entire multiverse.