"Hello," her first release since the Oscar-winning James Bond theme "Skyfall," is vintage Adele -- a huge, emotional ballad directed at a lost lover.
The single, along with a moody, sepia-toned video
, soon had the London-born singer's name trending worldwide on Twitter -- with fans gushing about the new track.
"Wow. That's how you do a comeback track!" tweeted British actor Andrew Hayden-Smith.
British broadcaster Fearne Cotton tweeted that the singer was looking "insanely beautiful in her video and proving again she has the voice of the century."
Twitter use Anuj Sharma wrote: "Heard the song 10 times already... Gives me chills every time."
Adele appeared on the "BBC Radio 1 Breakfast Show" to debut the track, confessing after it had played: "I feel so sick. I'm so nervous. ... I thought I'd burst into tears."
The singer agreed when asked if it was "Day One of being back as Adele."
"I obviously want people to like it," she said. "When I wrote it, I knew this would be the first thing everyone heard from me. I want to surprise people."
Fans had been teased for days about the impending release of new material from the singer.
In a personal statement posted Wednesday on her official social media accounts, Adele hinted that her long-awaited third album, titled "25," will explore her journey to adulthood and self-acceptance.
"My last record was a breakup record and if I had to label this one I would call it a make-up record," she said. "I'm making up with myself. Making up for lost time. Making up with everything I ever did and never did."
The 27-year-old singer also offered an apology of sorts for the delay in readying the new album, which has been rumored to be coming, oh, anytime now since about 2013.
" '25' is about getting to know who I've become without (realizing)," she said. "And I'm sorry it took so long, but you know, life happened."
With "25," Adele continues her pattern of titling albums after her age at the time she wrote and recorded them.
In a follow-up post Thursday, she said the album will go on sale November 20.
Released in 2011, Adele's sophomore album, "21," sold more than 11 million copies in the United States
to become the biggest-selling record this decade. The album swept the 2012 Grammys, winning album of the year and song of the year for "Rolling in the Deep."
Adele has kept a low profile since then, giving birth to a son with businessman Simon Konecki in 2012 and resurfacing for occasional projects such as the theme song to the James Bond movie "Skyfall" (2012), which won her and Paul Epworth an Oscar.