1. An early system on the IBM 650. [Listed in CACM 2(5):16, May 1959]. 2. Serial Infrared. An infraredstandard from IrDA, part of IrDA DATa. SIR supports asynchronous communicATions AT 9600 bps - 115.2 Kbps, AT a distance of up to 1 metre. [Reference?] (1999-10-14)