From MagicaVoxel Community Wiki
A voxel represents a value on a regular grid in three-dimensional space. [...] The word voxel originated by analogy with the word "pixel", with vo representing "volume" and el representing "element"
- from Wikipedia
These cells are often called voxels (volume elements), in analogy to pixels.
- in the book Computer Graphics: Principles and Practice
A cubic 3D equivalent to the square 2D pixel. The name is a combination of the terms "Volumetric" and "Pixel". Used to store smoke and fire data from physics simulations.
- from the Blender manual