They are unit intervals.
To graph a negitive . You would go three spaces back from zero.
it is how many spaces the number is away from 0 on the numberline. always positive.
Intercostal spaces
The spaces between leaf veins are called areoles or areolae.
pore spaces
the spaces between the teeth of a comb are called umpernaters :) that's their scientific name.
Rhythm
cementation
The tufted vertical ridges are called wales. The apparent "spaces" between the wales are actually the base fabric called the ground (which can be plain or twill).
If the spaces have been inserted between the letters it is called kerning. If the spaces are put between paragraphs or other elements it is simply called formatting (layout).
What is outside the cell
Stroma