I know this has got to be a dumb question, but what is the proper technical term used to describe the multiplier of a base mag range?

For example, a 2-12 magnification range optic is double of 1-6. What's the term for that doubling?

Like the Leupold VH6HD which has a 6:1 zoom ratio can be 1-6, 2-12, 3-18, and 4-24.