| Abbreviation | Definition |
|---|---|
| RXO | Receiver Output |
| RXU | Receiver Unit |
| RXV | Receiver Video |
| RZ | Return to Zero |
| S | Scattering |
| S | Sensor |
| S | Siemans (inverse of Ohms - unit of admittance) |
| S | Sound |
| S | Source |
| S | Switch |
| S/A | Sensor/Actuator |
| S/D | Source/Drain |
| S/N | Serial Number |
| S/S | Seconds per Step |
| SA | Sampling Actuation |
| SA | Structured Audio |
| SA | Symbol Addressing |
| SA/SD | Structured Analysis / Structured Design |
| SAA | Static Automated Analysis |
| SAB | Sensor/Actuator Bus |