Neume - Wikipedia
A neume (njuːm; sometimes spelled neum)[1][2][3] is the basic element of Western and Eastern systems of musical notation prior to the invention of five-line staff notation.
The earliest neumes were inflective marks that indicated the general shape but not necessarily the exact notes or rhythms to be sung. Later developments included the use of heightened neumes that showed the relative pitches between neumes, and the creation of a four-line musical staff that identified particular pitches. Neumes do not generally indicate rhythm, but additional symbols were sometimes juxtaposed with neumes to indicate changes in articulation, duration, or tempo.