Meaning

noun the property of being both obvious and offensive

originFormed 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…

Etymology from Wiktionary, CC BY-SA 3.0