The acronym SEM may refer to any one of the following:

In Economics and Management:

• Single European Market (or internal market), a single market of the European Union
• Stock Exchange of Mauritius, the organization responsible for the operation of the primary stock exchange of the island nation of Mauritius
• Strategic Enrollment Management, an element of planning for new growth at a university or college

in Mathematics and Statistics:

• Simultaneous equations models, a form of statistical model in the form of a set of linear simultaneous equations
• Standard error of the mean, the standard deviation of a sample mean over all possible samples drawn from the population
• Structural equation modeling, a general term used to describe a set of statistical methods designed to test a conceptual or theoretical model

in Science and Technology:

• Scanning electron microscope, a type of electron microscope that produces images by scanning a sample with a focused beam of electrons
• Space Experiment Module, a scientific experiment that was aboard the space shuttle Columbia during its destruction
• Spectral Emission Mask, a type of filter applied to radio or optical transmissions to reduce or eliminate adjacent-channel interference
• Sistema Eléctrico de Magallanes, a power grid serving the Magallanes and Antarctica Chilena region of Chile
• Synthesizer Expansion Module, part of an Oberheim Electronics modular synthesizer system

in Computing:

• Search engine marketing, a form of internet marketing that involves the promotion of web sites by increasing their visibility in search engine results pages
• Security event manager, a computerized tool used to centralize the storage and interpretation of events (or logs) generated by software running on a network

Schools, Organizations and Societies:

• Science and Engineering Magnet, a magnet college preparatory high school located in the Dallas Independent School District
• Stockholm Ethnographical Museum, a science museum in Sweden focused on the etnography, or cultural anthropology, of various peoples from around the world
• Swedish Evangelical Mission, an independent organization within the Church of Sweden
• Society for Ethnomusicology, a major international ethnomusicology association located in Indiana, in the U.S.

Places:

• Craig Field, a small, public-use airport in Alabama in the U.S., with the IATA airport code of SEM
• Sem, a commune in the Ariège department in southwestern France
• Sem, a village in Tønsberg in Vestfold county, Norway

miscellaneous:

• Š?m, S?m or Shem, one of the sons of Noah in the Bible
• Georges Goursat (a.k.a. Sem), a French caricaturist who was famous during the Belle Époque
• Super Étendard Modernisé, a strike fighter aircraft designed for and used by the French Navy
• Self-evaluation maintenance theory, a psychological theory that refers to discrepancies between two people in a relationship
• Sequential Excavation Method (or New Austrian Tunnelling method), a popular method of modern tunnel design and construction
• Sports and exercise medicine, a branch of medicine that deals with physical fitness and the treatment and prevention of injuries related to sports and exercise