bla-tant / blāt-nt
1. disagreeably loud and noisy
It was different from the dance- hall piano-banging and blatant brass bands he had heard.
From “Martin Eden” by Jack London, 1876 – 1916
2. boldly obvious; conspicuous, with no attempt to hide
It is sometimes well for a blatant error to draw attention to overmodest truths.
Jean Rostand 1894-1977
Coined by the English poet Edmund Spenser, it comes from same onomatopoetic root as the Latin verbs blat(t)ero, blat(t)erare, blat(t)eravi, blat(t)eratum and blatio, blatire, ___, ___ and the English verbs blat or bleat, all of which indicate a noisy prating, babbling, or the sound made by animals like sheep or goats.
Thank you to Allen Ward for providing the etymology of blatant.