An etymology is a history of a word, option (a). It involves tracing the origins and development of a word, including its root form, other related words, and any changes in meaning or pronunciation over time. It primarily focuses on the linguistic evolution of a particular word or term rather than a general history of the English language, making option (b) incorrect. Etymologies are not just a list of entries, so option (c) is also incorrect. Finally, etymologies are not synonymous lists, so option (d) is also incorrect.
