blatancy

The story

Formed by analogy with the way that words that end in -ant that are derived from French typically form their noun forms. This is erroneous logic in this case, however, because blatant does not derive in any way from French, but is rather a native English formation using native English word parts (bleat and -and), that only later had its ending slightly modified to fit more with other words that were more commonly used, that happened to have the French-derived -ant suffix. Some other examples of the -and suffix changing to -ant over time are flippant and blicant.