Alamiyyah (Arabic: الأعلمية) refers to the concept of following the most learned jurist. General consensus amongst scholars of the Usuli school of thought is that it is an obligation for a lay person to do Taqleed of the most learned of the Shi’ite jurists, who is known as the alam (الأعلم). Scholars of the Akhbari and the Kirmani Saykhi schools of thought do not consider this to be a condition at all, and reject the concept of taqleed in its entirety.
The definition of most learned is the scholar who is the best at making legal deductions. It does not mean the scholar whose rulings are most correct, since it would be impossible to know such a thing. Ayatullah Muhammad Taqi al-Hakim writes that, if this were the case, then it would be required to follow the scholar who is most precautious, since by virtue of his precaution, he would be erring on the safe side on most issues, and his rulings would naturally be more correct than those of other jurists. The quality of being most learned is known as alamiyyah (الأعلمية).