If that's your only argument, I've already pointed out the fallacy by indicating that, from a sample, most of those hits are part of compound nouns and are not the use of 'garment' for a single item of clothing (See post #11). Whether the word 'garment' is common or not is not, and never has been, at issue.
If you want to start a new thread asking whether 'garment' is a common word in English, I'll agree with you.
If you want to start a thread asking the difference between i) whether 'garment is a common word, and ii) whether 'garment' is commonly used for a single item of clothing, I can explain that again too.
If you want to know how X can get 100,000,000 Google hits and yet not be used commonly to mean Y, I can also explain that.