For a long time we didn't have a word for it in the west, other than distance.
Nowadays we often use 'the pocket' to describe striking range.
In Japan they use the term maai to describe the different distances between two people in a fight.
You have ultra long range where you can run away.
You have kicking range.
You have punching range.
You have clinching and close striking range.
And you have the ability to change ranges.
This understanding makes you 3 dimensional. Getting outside of your opponents range and into yours, you play with distances and angles.
In SFDOJO we had a skull with two sickles on our rashguards to represent the different ranges.