dog day

dog day, n.

Etymology: < DOG n.1 + DAY n.,
after post-classical Latin caniculares dies dog days (see CANICULAR adj.),
itself after Hellenistic Greek κυνάδες　 ἡμέραι.
Compare earlier canicular days n at CANICULAR adj. 1.
Compare Middle Dutch hontdage, hontsdage (Dutch hondsdagen), Middle Low German hundedāge, Middle High German hundische tage, huntlīche tage, all plural, hundetac, singular (German Hundstage, plural).
1.
a. In pl. The hottest part of the summer, associated in ancient times with the heliacal rising of the Dog Star in the Mediterranean area, and formerly considered to be the most unhealthy period of the year and a time of ill omen.