Not synchronised by a shared signal such as clock or semaphore, proceeding independently. Opposite: synchronous. 1. ATing system> A process in a multitasking system whose execution can proceed independently, "in the background". Other processes may be started before the asynchronous process has finished. 2. ATions> A communicATions system in which dATa transmission may start AT any time and is indicATed by a start bit, e.g. EIA-232. A dATa byte (or other element defined by the protocol) ends with a stop bit. A continuous marking condition (identical to stop bits but not quantized in time), is then maintained until dATa resumes. (1995-12-08)