Generalized sequential machine in automata theory

GSM is a common abbreviation for Global System for Mobile Communications (Groupe Spécial Mobile), the European group set up to establish European mobile telephony protocols and for telephony services using those protocols. GSM may also refer to:

The ICAO code for low cost airline Flyglobespan

Gameshow Marathon (US TV series), an American television series based on the above

Gameshow Marathon (UK game show), a British television series

Grams per square metre, an indication of paper density

A file format and filename extension used by the company Graphisoft for ArchiCAD library parts mainly written in Geometric Description Language (GDL)

Glass Sport Motors, a former South African car company

Garrison Sergeant Major, a warrant officer appointment in the British Army

General Service Medal, a British campaign medal

Graduate Studies in Mathematics, a series of mathematics texts published by the American Mathematical Society

A wine blend consisting of approximately equal parts grenache, shiraz, and mourvèdre

A file format and filename extension, with GSM-like codified voice (with variants. Full Rate is the simplest), as used by GSM mobile phones and other sound handling programs, like asterisk (PBX) or SoX.