'nationalistically' originates from English, specifically the word 'nationalistic' (formed from 'national' + suffix '-istic'), with the adverbial suffix '-ally' (from Latin '-alis'); 'national' ultimately comes from Latin 'natio' meaning 'birth, people, nation'.

'national' developed from Latin 'natio' via Old French 'nacion' and Middle English 'nation'; the adjective 'nationalistic' arose in modern English (19th century) to mean relating to nationalism or excessive devotion to one's nation, and 'nationalistically' was formed by adding the adverbial suffix to that adjective.

Initially related to 'birth' or 'a group of people' (from Latin 'natio'), the sense shifted toward 'relating to the political concept of nationhood'; over time 'nationalistic' gained the connotation of strong or excessive patriotism, and 'nationalistically' now means 'in a nationalistic manner' (often implying bias or exclusion).