Boolean
A boolean value (named after George Boole) is a binary value comprised of a single bit. That is to say, it can be one of only two possible values. It's either on or off; true or false; one or zero (as with a binary digit, or bit for short); in transistor-transistor logic gates, +5 volts or 0 volts.
In the context of synthesisers, triggers and gates are boolean values.
Computer science: Bit | Boolean