ETYM Greek; syn with + kronos time. Related to Chronicle.
1. Occurring or existing at the same time or having the same period or phase; SYN. synchronal, synchronic.
2. (Digital communication) Pertaining to a transmission technique that requires a common clock signal (a timing reference) between the communicating devices in order to coordinate their transmissions.
3. Pertaining to or happening at same time.
4. Regular. Most communication within a computer system is synchronous, controlled by the computer's own internal clock, while communication between computers is usually asynchronous. Synchronous telecommunications are, however, becoming more widely used.

Occurring at the same time. In computer transmissions, a reference to activity governed by a clock or by synchronized timing.