In telecommunication, a n -ary code is a code that has n significant conditions, where n is a positive integer greater than 1. The integer substituted for n indicates the specific number of significant conditions, i.e., quantization states, in the code. For example, an 8-ary code has eight significant conditions and can convey three bits per code symbol. A prefix that indicates an integer, e.g., "bi," "tern," or "quater," may be used in lieu of a numeral, to produce "binary," "ternary," or "quaternary" (2, 3, and 4 states respectively).

Source: from Federal Standard 1037C and from MIL-STD-188