Hold the picture of a town in late August. The air does not move. The street is empty between noon and five, the shop keeps half its lights off, and everyone is quietly waiting for the season to turn. That is the whole word: not one hot day, but a long flat stretch where nothing can get going — and a stretch that everyone knows will end. Take the heat out of that picture and leave the rest, and you have the way English uses it for bad years in a business or a career.
Dog days is a word-for-word translation of Latin diēs caniculārēs, itself a translation of a Greek phrase meaning 'dog days'. The dog is Sirius, the Dog Star: in antiquity its rising with the sun fell around late July, and those weeks were held to be the hottest and least healthy of the year.
dog days 是拉丁文 diēs caniculārēs 的逐字翻譯，而拉丁文又譯自意思相同的希臘說法。這裡的「狗」指的是天狼星（Sirius，狗星）。古代它偕日升起大約落在七月底，那幾週被認為是一年裡最熱、最不利健康的日子，名字就這樣沿用下來。
Wiktionary entry for dog days, etymology section (Latin diēs caniculārēs < Ancient Greek κυνάδες ἡμέραι, from Sirius) — kaikki:3f6f69a190036ae4:768054738:17690
One branch
熱到停住的那一段
兩個義項共用同一段時間感：長、沉、推不動、而且會過去。差別只在畫面裡留不留天氣。
noun · B2
The hottest, stickiest weeks of the year — in the northern half of the world, late July and August — when the air feels heavy and everything slows down. It is almost always used in the plural, with the: the dog days.
三伏天／酷暑期