The compound "then-president" is a modern English formation that combines the temporal adverb "then" with the title "president" to create a specific attributive adjective. The word "then" originates from a common Germanic adverb indicating a point in time, while "president" has a more complex Latinate history, deriving from praesidere (to sit before, guard, preside). The logic of the compound is straightforwardly literal: it identifies the individual who was the president at that (specified) time. This construction is particularly useful in historical or journalistic contexts to provide temporal clarity and avoid ambiguity when referring to a former holder of the office.

Structure: then (at that time) + president (head of state) - then: From Old English þonne, þænne, of Germanic origin; related to Dutch dan and German dann. Functions as an adverb/adjective meaning 'at that time'. - president: From Latin praesident- (sitting in front of, presiding), from praesidere (to preside). Functions as a noun meaning 'the head of a state or organization'.