What is a Pingo?

I was playing Words with Friends the other day against my cousin. The word that I played was pin, then she played back pingo! I was in disbelief that such a word existed, so I accused her of making the word up, even though this would require collusion with the makers of Words with Friends and I was was reasonably certain that, a) She didn't know the makers of Words with Friends, b) They wouldn't change a word on her request, even if they knew her, and, c) That she wasn't likely to expend the level of effort and planning required to add this word into the game, just to score a few points. Nevertheless I challenged her to use pingo in a sentence, as I was sure that even if it was an accepted word, she was probably just playing around with letters and didn't know the meaning.

My cousin rose to this challenge and replied with the sentence, "the Eskimo swore as he tripped over the pingo." I had a good laugh as I read this, firstly assuming that she had just made the sentence up for a laugh, but then thought it was a bit obscure to add that it was an Eskimo, so perhaps she had actually looked up the meaning (a thing that I could have done myself instead of challenging her, but it would have been less fun). So I decided to check the meaning as well (at this stage the fun was over and I really needed to know if she was making things up, or had actually checked the definition), sure enough the meaning of the word pingo is, "a hill of soil-covered ice pushed up by hydrostatic pressure in an area of permafrost." So it would be reasonable to assume that Eskimos would see pingos all the time, and understandably might swear as they trip over them.  Obviously my cousin had looked up the definition and came to the same conclusions as myself. So I had to admit that pingo was an acceptable word, however I would still like to point out that my spell checker highlights pingo as a misspelt word, so I am not the only one in disbelief!

Check the definition of pingo yourself at dictionary.com.