blithering
adjective
[ ˈblɪð(ə)rɪŋ ]
• complete; utter (used to express annoyance or contempt).
• "a blithering idiot"
Origin:
late 19th century: from blither + -ing2.
blither
verb
• talk in a long-winded way without making very much sense.
• "I won't blither on too much about the job itself"
Origin:
variant form of blather.