A register. The record of a court of justice. The decree of a judge. In the Qur’an, the word occurs when it is used for the angel which has charge of the register of the fate of mankind, or accorwzig to others, it may mean the roll itself.
Surah xxi. 104; “The day when we will roll up the heavens as as-Sijill tolls up his books; as We produced it at the first creation, will we bring it back again”
Based on Hughes, Dictionary of Islam