The definition of a chronograph is an instrument that measures intervals of time.
An example of a chronograph is a stopwatch which is used to measure how long an event lasts.
any of various instruments, as a stopwatch, for measuring and recording brief, precisely spaced intervals of time
Origin of chronographchrono- + -graph
An instrument that registers or graphically records time intervals such as the duration of an event.
From Ancient Greek χρονογράφος (khronographos, “chronicler”).