One theory says that "Geidai" (the title of the performance) was shortened into "Gedai," and the other theory says that "Gedai" has its origin in the short and main title written on the outer part of the picture scroll, which was called "Gedai" from ancient times to the medieval age.
「芸題」（げいだい）が詰まって「げだい」になったとする説もあるが、古代から中世にかけては絵巻物の外側に書かれた短い本題を「外題」と言っており、これが起源だとする説もある。