Plural of diaulos; in ancient Greece, a double-piped wind instrument or a race course with a turn at the far end.
Greek 'diaulos' from 'dia-' (double, across) and 'aulos' (pipe or hallway), originally describing the two-reed pipe, later applied to race courses with turning points.
The Greeks were clever with word reuse—'diaulos' meant both a musical instrument AND a type of race course, because both required going in two directions or having two parts working together.
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