samaaegsusest

Samaeegsusest is an Estonian term referring to the state or quality of occurring at the same time, i.e., simultaneity. The word is built from samaaeg ("the same time") and the suffix -sus, with -est in the form used in phrases denoting "from simultaneity" or "of simultaneity."

In physics, simultaneity is the question of whether two distant events are perceived as occurring at the same moment. In Einstein's theory of relativity, simultaneity is relative to the observer's frame of reference; there is no absolute universal time at which events occur. The classic train and platform thought experiment illustrates how signals synchronized in one frame do not remain synchronized in another, highlighting the relativity of simultaneity.

In philosophy and cognitive science, samaaegsusest is used to discuss how humans perceive timing and coordinate actions, as well as the mathematical treatment of concurrent processes in computer science and statistics. The concept is also relevant in linguistics and everyday language when describing events that occur together or in close temporal proximity.

In Estonian scholarly usage, the term appears across disciplines to describe temporal alignment or concurrency, whether in physical events, mental processes, or data streams. See also simultaneity; relativity of simultaneity; time; synchrony.