Mullah is a general term, in Persian, Turkic and South Asian usage, for a locally trained religious functionary, the man who carries the ordinary religious business of a community.
The everyday religious office
The mullah is the mosque teacher, the instructor of children in the Quran, and the man who conducts the religious ceremonies of a village or a neighbourhood, the naming, the marriage, the funeral, so the office is the practical and local face of Islam rather than a rank of high scholarship. His training may range from modest to considerable, but the term denotes his function in the community more than any fixed level of learning, and there is no ordination, the standing resting on recognised competence and on the acceptance of the community he serves.
A term that shifts by place and tone
The word derives from an Arabic term for master or lord and is applied broadly, and its tone varies: in some settings it is a respectful title for a learned man, in others it is used loosely or even dismissively for any minor cleric, and in the Shia world of Iran it has attached to the whole clerical class. The office it most often names, the local teacher and ritual functionary who serves the ordinary religious needs of a community, has a close counterpart in many traditions, but the particular associations of the word belong to the Persian, Turkic and South Asian Muslim worlds in which it is used.