Is it permissible to address someone who has not memorized the entire Qur’an as “Sheikh So-and-so”?

The word "Sheikh" is used, customarily and linguistically, to denote several meanings, including a scholar, or a specialist in the sciences of Sharia, or an elder, or a person of religious devotion, or a dignified individual. Therefore, there is no religious impediment to using it for someone who has not memorized the entire Quran, especially if they possess some of these qualities.