What is "rectification"?

Howdy folks, I just started another thread in the MIG section looking for the term inductance to be explained. I have several more terms that aren't in the "glossary" but I feel are necessary to know (for me, and I hope others find the info useful too). On my first TIG welding machine, which was 35 years old, there were 2 knobs to adjust the AC arc, one was Hi frequency intensity, the other was called arc stability. In the factory manual, All I got for an explanation for either was to "adjust for best results". However, an old sales brochure stated something to the effect that the arc stabilization would result in a "controlled lack of rectification" (even had a patent) Huh?????? So, In the short time I've been a part of the welding community, I have yet to hear or read a comment anything like "Yup, if it weren't for all that rectification goin' on, them would be some darn nice welds". Nor has anyone posted anything like "Help! rectification is RUINING me!: So, I'm going out on a limb here by guessing that rectification, as far as welding goes, is bad. But I recall the possibility that there is a component in some welders called a "rectifier". Can you see where one might get just a wee bit confused? If anybody out there knows the meaning of this word, and/or it's relationship to the welding world, please post it. Thanks!!!

The English term 'rectification' has several different meanings:

1: The conversion of alternating current to direct current
2: determination of the length of a curve; finding a straight line equal in length to a given curve
3: the act of offering an improvement to replace a mistake; setting right
4: (chemistry) the process of refinement or purification of a substance by distillation

Basically it takes an AC or modified DC and attempts to smooth or change it. Diodes will clip (block) one side of the AC, caps will help smoothing as well. Hard to explain without pictures. But look up power supplies and rectifiers in google. Will be plenty on bridge rectifiers and smoothing.