Sometimes you will come across the use of Latin abbreviations in reading lists and in references or bibliographies. They are used as shorthand to accommodate instances where multiple authors contribute to a book/article, or where a publication is cited repeatedly in a reading list or work.
Here are some of the more common abbreviations that you may well come across.
et al.
This is an abbreviation of the Latin phrase et alii, meaning ‘and others’. When a work has more than two authors it is common within references to give the first author only and follow it with ‘et al.’ to indicate that there are other authors.
Ibid.
This is an abbreviation of the Latin word ibidem, meaning "in the same place". If you see this in a reading list, it refers to the work in the immediately preceding reference, and stands for all identical elements of the reference.
Id.
This is an abbreviation of the Latin word Idem, meaning "the same". It is used in a reference in place of an author's name to indicate that the author is the same as in the preceding reference.
Loc. cit.
This is an abbreviation of the Latin phrase loco citato, meaning ‘in the place cited’. It refers to the work in the immediately preceding reference, and can be used instead of ibid. when all the citation details (including page numbers) are identical.
Op. cit.
This is an abbreviation of the Latin phrase opere citato, and means "in the work already cited". It refers to a work in a previous reference, but not the immediately preceding one. It is preceded by the author’s name and followed by the page number (s). The publication date is also included if there is more than one work by the same author in the references. Check your reading list for the previous, fully cited, reference to the same work.