tristate

1. not comparableHaving, or pertaining to, three distinct states.

   This tristate logic deals with true, false, and unknown values.

2. not comparableOf, pertaining to, or characteristic of a region in the United States where three state borders come to a single point.

   The event will be sponsored by several tristate businesses.

plural tristates

1. computingA variable, etc. that can take any of three distinct values.

   Configuration options that control the build process are either Booleans or tristates.

   2010, Robert Love, Linux Kernel Development, page 14

   1 more example

   The 4 input ports are simply tristates that can be addressed to enable the data from any one of them to be read by the standard input port of the printer interface.

   2000, John Blankenship, C is for Control

2. capitalizedoftenThe area in some regions of the United States where three state borders come to a single point.

   The Tristate is on alert after a rash of home burglaries.