Say it ain't so...

So I retired.
Several weeks ago, I read the annual list of words added to the Merriam-Webster's Collegiate Dictionary, Eleventh Edition. This year, the list includes words such as earmark, goji, memory foam, shawarma, and webisode. So, OK, now I can feel free to use these words in a sentence without a trace of guilt, and in truth, use them confidently because I know their meaning. I have memory foam pillows and I love them. I once watched a webisode of 24 because I messed up the Tivo. Naproxen was another word added this year, well, heck that drug has been around since the early '80s and in my profession have used it indiscriminately and without knowing I was committing an etymologic faux pas.
Nevertheless, it's always good to know your language is legitimized.
Since I have been reading these lists, I have often wondered about the word ain't. One of the first things you learn in grade school is that this little word is NOT REALLY A WORD. I never quite understood why, but always harbored the knowledge that it was right up there with picking your nose, not washing your hands after peeing, or putting bananas in the refrigerator. I remember my first-grade teacher wagging her index finger while warning us of the dire consequences of such talk. It's likely I was in college before I actually used it. When I have used the word ain't in a sentence, I have felt the ugly twinge of guilt and briefly looked around for uniformed and armed Funk or Wagnell.
Come to find out ain't IS in the dictionary, meaning "am not, have not or do not". Good. Things have changed in 55 years. However, there is an additional comment that while increasing in popularity, it is widely disapproved as nonstandard and more common in the habitual speech of the less educated.
Apparently we are not yet totally vindicated. By using this word, I have cast doubt on my 7 years of postgraduate education and well, yes, my entire profession.

Ain't it the truth? I retired.