Brilliant, stunning, mind-blowing, fabulous; terrific, gorgeous, out of this world. Expressive colloquial adjective derived from the verb обалдеть (to be stunned/dumbfounded), which comes from the older root балда (blockhead/fool—originally meaning to be driven senseless or dazed). It describes someone or something that is absolutely wonderful, high-quality, or visually spectacular (какой обалденный вид из окна! — “what an brilliant view from the window!”; ты выглядишь просто обалденно — “you look absolutely stunning”).
Квартира — обалденная… Ковры мохнатые по щиколотку, лампочки и столики во всех местах напиханы, бар забит пестрым суперпойлом — это он удачно зашел. Нет, в Париже хорошо.
The flat was smashing… Velvet carpets up to the ankles, lamps and tables standing in all places, the bar filled with neat, classy drinks — this had been his lucky move. You can’t say anything, it’s nice in Paris.
(Михаил И. Веллер, Легенда о стажёре, 1993)
