dog days

Meanings

1. The days following the heliacal rising of Sirius, now in early August (Gregorian) at dates varying by latitude.
2. The unpleasantly hot days of late summer.
3. Any similar period of inactivity, laziness, or stagnation.

Etymology

Calque of Latin diēs caniculārēs (“puppy days”), a calque of Ancient Greek κυνάδες ἡμέραι (kunádes hēmérai, “dog days”), from κυνάς (kunás, “of or related to dogs”), from Κῠ́ων (Kŭ́ōn, “the Dog”) in reference to the star Sirius, which appears in Homeric Greek as "Orion's dog". The return of Sirius to the night sky (its heliacal rising), occurring in antiquity around July 25 (Athens) or 29 (Rome), was considered by the Greeks and Romans to herald what were considered the hottest, least healthy, and least lucky days of summer.