In comics, it means team-up, but in music, a "crossover event" means performing at halftime of the Super Bowl, or recording the theme song to a "James Bond" movie.

Legendary musical innovators Radiohead were set for a fun crossover when they were commissioned to contribute the title track to "Spectre," this year's latest Bond escapade, but that privilege ultimately went to Sam Smith with his song "Writing's On The Wall," which he admits took just 20 minutes to pen.

As a holiday gift to fans, Radiohead frontman Thom Yorke released the unused commission to the band's SoundCloud page, making it free for download.

In Christmas-morning social media posts, Yorke explained. "Last year, we were asked to write a tune for the Bond movie, 'Spectre,'" he Tweeted. "It didn't work out, but became something of our own, which we love very much. As the year closes, we thought you might like to hear it. Merry Christmas. May the force be with you ..."

The giveaway is in keeping with the band's long history of fan-friendly digital distribution.

Last year we were asked to write a tune for Bond movie Spectre. Yes we were ...........

— Thom Yorke (@thomyorke) December 25, 2015

... It didn't work out ... but became something of our own which we love very much .... — Thom Yorke (@thomyorke) December 25, 2015

.. As the year closes we thought you might like to hear it. Merry Christmas. May the force be with you ... https://t.co/BXN8MQKJyQ

— Thom Yorke (@thomyorke) December 25, 2015

"Spectre" and "Writing's On The Wall" both echo the tonal melancholy of the Sam Mendes feature, but reveal telling distinctions in how musicians Smith and Radiohead use vocals and composition to evoke drama in their respective works. While both have soaring moments, looking back, Radiohead's claustrophobic vision may even be more in keeping with the Bond film's feel than Smith's more vulnerable take.

Which version do you prefer? Which feels more thematically true to Daniel Craig's fourth turn as 007? Sound off in the comments.