A verb meaning to add light and shimmer or to decorate by hand with gold, silver and coloured designs.
In Arabic,Turkish and Persian the term presents itself the same in all three languages - Tezhip/Tahdhib/تذهيب
Islamic illustration is the art of decorating the pages of the Quran and Arabic poetry books in gold with geometric or biomorphic patterns. Originally, calligraphy developed into an art form as a result of the Quran being so highly regarded as the word of Allah, that its visual representation was to also be carefully considered in order to reflect its importance.
However, as the art developed in the Muslim world, artists found that calligraphy was not enough and therefore took it a step further by incorporating gold embellishments to decorate the Quran to physically represent the enlightenment that comes from the book of Allah. On most Qurans, the cover and the frontal pieces are always very elaborate, however the rest of the pages are usually less decorated.
As time passed, this art form extended to other highly regarded books such as poetry and story books and collecting and gifting such highly adorned books was considered a symbol of status.
Usually, the embellishment of the Quran would be executed upon the completion of the text by the calligrapher, however, it was not uncommon for them to have been the same person sometimes. If they were not the same person, it is likely they were working together, collaborating in the planning of the page layout and the format of the volume.