(Indo-European studies) A system which describes how certain Proto-Indo-European words are derived from one another.

(travel, aviation) a multi-access reservation system used by the travel industry and airlines.

(astronomy) A geocentric model of the solar system, described by the eponymous astronomer.

The hierarchical organization of the kitchen staff in a restaurant into small teams or individuals, each responsible for a type of food (starters, mains etc) under the overall control of a head chef.

(object-oriented programming) A concept for computer language types where a primitive type can support methods and encapsulation, but only reference types support virtual methods and specialization.

plural of unified type system

plural of Abt system

(rail transport) A rail system used in mountainous terrain with multiple cograils.

(crystallography) Any of the seven distinct symmetry classifications of crystals: cubic, tetragonal, hexagonal, orthorhombic, monoclinic, triclinic and trigonal.

plural of writing system