Hey no worries! Basically a written copy of the music they are playing. Going “scoreless” is a conductor going to the podium without any sheet music. The term “score”, in an opera context for example, is end-to-end, all of the instrumental + vocal parts written out in musical notation.

Basically a book of all the music to be played

Oh cool! Yes, in Nilsson’s biography she explains Toscanini doing this for this reason and then claims it set off a trend for people to do it who didn’t really need to. Thanks for sharing the Toscanini book, I love classical music biographies!

In case anyone’s interested, here’s the excerpt from “La Nilsson - My Life in Opera” in which she discusses it — 10/10 recommend this book, shes very funny and as you can see, doesn’t hold back!:

“It is a kind of status symbol for conductors to conduct without a score. It is said that Toscanini started this fad, but the reason he conducted without score is that his vision was so poor he had to conduct from memory. A concert conducted without a score is admirable but after all, the musicians have their notes right in front of them. In the worst case the conductor can always, as someone put it, follow the orchestra. But when the conductor of an opera has the soloists, chorus (and, in Karajan’s case, telephone and lighting) to control, it is totally irresponsible to conduct from memory. Just being aware that the conductor has no score before him makes the singers nervous and insecure. Singers have a lot to memorize and a Wagner opera is generally four to five hours long. I have lived through several totally unnecessary catastrophes with these “scoreless” exhibitionists. It is extremely difficult artistically to be subjected to this. Just such an incident happened in a Tristan performance with Karajan. After singing in act 1 continually for seventy-eight minutes, and with the intermission not providing sufficient rest, I found myself completely disoriented in act 2. Indeed, I drew a blank and lost any sense of where I was in the music. Karajan noticed my situation immediately, but as he was conducting from memory he was of no help to me. He turned to the first violins and pretended to be very busy with them. The half-asleep prompter was not to be brought around and it seemed to me an eternity until I was back on track, at which point Karajan resumed his normal stance and his usual transcendental air. When the renowned conductor Knappertsbusch was asked why he did not conduct from memory, he answered, “Because I can read music.””