If we look at the word "internet", we can see that it was virtually unused until around 1990. Next, if we look at the word "wifi" we can see that there was a huge jump in around 2000. My question is that while the usage seems low, the word "wifi" was clearly being used in the 1800s. What did this word mean back then, or is this somehow a misinterpretation of the data?
It just means google was finding words that looked like wifi with its ocr, Internet is VERY hard to miss-ocr, there arn't any words that look like it.
You know OCR(Optical Character Recognition) is HARD, right? If you don't, now you do!
"Wifi" can be read by an ocr if the original was "Will" or "Wife", the ocr will often make mistakes, these 2 are most often mistaken, so google showes them as being used.
NOTE:This is as percentage, so googles ocr messes up 0.00000025% of the time out of all the words it ocr's, at the time on the second axis, in this case 1800.
The long percent can also be written as 10^-6*25%.