Is it permissible to call one's wife "Noura Al-Kubra" in emulation of the title "Khadijah Al-Kubra," or is this title specific to our Lady Khadijah, may Allah be pleased with her?

The title "Khadijah al-Kubra" (Khadijah the Great) has not been authentically established for the Prophet (peace and blessings be upon him) or for the early Muslims. Rather, it has been primarily used by the Shi'a, although some Sunni scholars have also used it. There is no harm in titling one's wife "Noura al-Kubra" (Noura the Great) to honor her and bring joy to her, without believing in any special virtue or similarity to the title of Khadijah.