nearinstantaneous

Nearinstantaneous describes a process or event that happens so quickly that its duration is effectively negligible within a given context, though it is not truly instantaneous. The phrase is a qualitative descriptor used when the timescale of interest is much shorter than other relevant timescales in a system. Because the exact duration varies with the scenario and measurement methods, there is no universal numerical threshold for nearinstantaneous.

In practice, nearinstantaneous is often attached to signals, reactions, or actions with delays measured in nanoseconds to microseconds, or in some contexts, even faster. For example, electronic circuits can exhibit response times on the order of nanoseconds; optical communications can have latencies that are imperceptible for many applications; triggering events in scientific experiments are sometimes described as nearinstantaneous to indicate that the delay is negligible relative to the process being studied.

In computing and networking, nearinstantaneous may describe latencies that are small compared to workflow timescales, such as sub-millisecond delays in high-frequency trading networks or tightly synchronized sensor arrays.

Limitations: nothing can be truly instantaneous due to finite speeds of light and interaction times; measurement precision also imposes a limit on declaring something nearinstantaneous. The term is therefore relative: nearinstantaneous to one observer or system may not be so to another with different timing requirements.

Related concepts include instantaneous, latency, response time, and throughput.