The Illustrated Professional Dictionary Of Horology's definition of a complication, in the online edition, dates to 1961 and it is unhelpfully tautological: "State of being complicated. Cause of such https://www.apwx.co.uk state. Striking- and chronograph-mechanisms are https://www.rmwx.co.uk/Collection/rm-39/ complications." This is right up there with the same dictionary's definition https://www.rmwx.co.uk/Collection/rm-50/ of an extra flat watch, which is the laconic, "A watch that is extremely flat."