'transatlanticist' originates from English, formed by the prefix 'trans-' (meaning 'across'), the word 'Atlantic' (referring to the Atlantic Ocean), and the agentive suffix '-ist' (meaning 'person who advocates or practices').

'transatlanticist' developed in modern English by combining the adjective 'transatlantic' (itself from Latin/Greek elements meaning 'across the Atlantic') with the suffix '-ist' to denote a person holding a particular viewpoint or advocacy. 'Transatlantic' arose in the 19th century to describe relations across the Atlantic and was later used in compounds and agentive forms.

Initially the components referred to being 'across the Atlantic' or 'relating to the Atlantic'; over time the compound came to denote a person who actively advocates ties across the Atlantic, i.e., an advocate of transatlantic cooperation.