This is the 7170th most frequent Japanese word.
一体全体
"One whole entity; (intensifier) what in the world, what on earth."
Highlights confusion and disbelief toward understanding his explanation.
彼の説明は一体全体どうなっているのか、全く理解できない。
I absolutely can't understand how in the world his explanation makes sense.
Expresses amazement when asking for explanation regarding an achievement.
一体全体、君はどうやってこれを達成したの？
How in the world did you achieve this?
Used to emphasize a question and express incredulity.