Meaning of detoriate !

Yesterday I was trying to write the word "detoriate" in a word document and find it was throwing an error( red colored underline)!!
And while I was googling I got the below in one site"Sorry, no dictionaries indexed in the selected category contain the word detoriate." After more intensive search I find the word spells actually "deteriorating" instead of the word "detoriate" which I've written so far almost everywhere!
It puzzles me as it is such a common mistake which everyone makes and thinks they are writing the correct word!