What’s the complication?
Here is some explanation on the horological terms used in articles related to chronographs and chronometers on this site. The list is not exhaustive and is updated regularly.
Complication(s) - A special feature(s) in a watch that complicates the design of the watch movement to be more complicated.
Horology – An art or science of measuring time. A person engaged in horology is called a horologist.