The term 'footnote word' refers to a set of four Latin abbreviations commonly used in footnotes. The first is 'ibid, ' which stands for the Latin phrase 'ibidem, ' meaning 'in the same place.' The second is 'IDEM, ' which stands for the Latin phrase 'IDEM, ' meaning 'the same.' The third is 'ibidem, ' which is an extended form of 'ibid, ' and means 'in the same place, as before.' The fourth is 'passim, ' which stands for the Latin phrase 'passim, ' meaning 'here and there.' These terms are used to refer to previously cited sources in footnotes, allowing writers to avoid repeating the same information multiple times.