Calibration is the correct term, it's the gauge that is being "calibrated". This is no different from calibrating a thermometer or pressure gauge or any other measuring instrument which is "a means of adjusting a measurement device to get an accurate reading". From above link ....
I agree that is how it is supposed to work, but it doesn't. And that's the problem. When you "calibrate" a thermometer, pressure gauge, a set of scales, speedometer, volt meter, ruler or some other measuring device, you compare this measuring device with a "reference
standard", then you tweak/adjust the device to ensure 1 inch is exactly 1.00 inch, 19VDC is exactly 19.00VDC and 50°C is exactly 50.00°C, plus or minus what ever the allowed tolerances may be.
Look at CPU and motherboard voltage and temperature sensors. Even on quality CPUs and boards, those sensors are cheap, low tech devices that cost a couple cents each - if that. Then monitor those sensors with HWiNFO64, AIDA, the BIOS, Speccy or [
fill in the blank] and you will get different results with each. Why? Because none are "calibrated" to a reference standard.
it's the gauge that is being "calibrated".
So what reference standard is that gauge being calibrated against? Some sensor that cost 2¢ to make? What reference standard was that sensor "calibrated" against? The gauge is not being "calibrated". It is just being reset and "synchronized" to reflect some other
uncalibrated value.
When I am using my notebook, I want to know exactly how much battery run time I have left - especially now that my notebook battery is 8 years old! Yes, I realize that will vary depending on the task(s) I am performing now, but I'm okay with that. I also want to know exactly how long before I reach 100% charge - which, if I am idle should be fairly easy to accurately foretell.
It may be more a matter of semantics but that illustrates the bigger problem -
marketing weenies 
using technically incorrect terminology in user manuals and product promotion materials - again.
Calibration suggests some type of precision. Nothing precise is going on here.
I accept that the expression "
battery calibration" is a term that is here to stay. But just like "
wireless router" it is technically inaccurate. The battery is NOT being calibrated, just as there is technically no such thing as a router that is wireless.