day of the ox in midsummer; dog days of summer
Refers specifically to the day of the ox during the 土用 (doyō) period in midsummer, traditionally associated with eating eel to withstand the heat. Often used in the fuller phrase 土用の丑の日.
See also: 土用の丑の日
This year's midsummer day of the ox is July 30th.
There is a custom of eating eel on the midsummer day of the ox.
Compound of 土用 (doyō, 'the seasonal transition period') and 丑 (ushi, 'the ox sign of the Chinese zodiac'). The exact historical origin of the eel-eating custom is uncertain.