Society of Motion Picture and Television Engineers.

The SMPTE standards have been very important for cinematography and television, especially for professional applications.

Their importance has decreased since the transition to digital video, when many relevant standards have been issued by other organizations, but many SMPTE standards are still important, especially regarding the formats used for distributing digital movies for movie theaters.

https://en.wikipedia.org/wiki/Society_of_Motion_Picture_and_...

I had the same question. I clicked on their menu About > Who is SMPTE page and it didn't define the acronym either.

Then I scrolled to the bottom of the page and I did see it in the footer: SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS

Today I learned

I thought it was the Transatlantic album (StoltMorsePortnoyTrewavas)

I saw it and thought it was an extension to the the SMTP standard.

Explained here: https://www.youtube.com/watch?v=jk9xpH5aUtk

Also the name of prog supergroup Transatlantic's first album, SMPT:E, a play on the band members names.