Any of numerous attractively coloured freshwater South American and African fishes (family Characidae), often kept in home aquariums. Tetras are small, lively, hardy, and unaggressive. The slender neon tetra (Paracheirodon, or Hyphessobrycon, innesi) has gleaming red hind parts and a neonlike blue-green stripe on its sides. The glowlight tetra (Hemigrammus erythrozonus) has a shining red stripe along each side. The body of the silver tetra (Ctenobrycon spilurus) is flattened sidewise
A combining form (also used adjectively) denoting four proportional or combining parts of the substance or ingredient denoted by the term to which it is prefixed, as in tetra-chloride, tetroxide
(Terrestrial Trunked RAdio) TETRA is a set of standards developed by the European Telecommunications Standardisation Institute (ETSI) that describes a common mobile radio communications infrastructure throughout Europe This infrastructure is targeted primarily at the mobile radio needs of public safety groups (such as police and fire departments), utility companies, and other enterprises that provide voice and data communications services All of these groups have been high-end users of private/professional mobile radio (PMR) or public access mobile radio (PAMR) technology
TErrestrial Trunked RAdio TETRA is a standard for digital, cellular, trunked radio networks TETRA has been designed and developed notably as a mobile system for handling emergency and safety tasks