What is a vacation? This word is familiar even to a first grader who has barely crossed the threshold of a school. Why are periods free from studies so called? But with vacations for workers and employees everything is extremely clear and simple. Let go to rest - so, provided a long weekend. What about the holidays? Although it sounds beautiful, it is completely incomprehensible how the word was formed and where it came from in Russian.
Echoes of Greek and Roman Mythology
Anyone who likes to look at the night sky, probably knows the name of the brightest star - this is Sirius, located in the constellation Canis Major. According to scientists, the name of the star comes from the ancient Greek word sirios, which meant "hot, scorching." Between mid-July and the last days of September, when the distance between Sirius and the Sun becomes minimal, unbearable heat sets in in Greece. The ancient Greeks believed that it was the brightest star in the horizon that sent summer heat to the earth. Therefore, all such a period was called by the name of a scorching star.

It was no less hot in the summer in Ancient Rome. But since the Romans affectionately called Sirius the “dog” (in Latin canus), the hot months were called “dog days” (dies caniculares). At that time, city dwellers strove to leave closer to nature, the Roman parliament ceased to work, school students were dismissed home, that is, the holidays were coming. This word was borrowed in some other European languages to refer to particularly hot summer days. True, it was used in the singular - "vacation".
The best time of the year for students and schoolchildren
In Russia, public educational institutions practically did not exist until the 17th century. Noble children were taught by specially hired teachers and tutors; for the rest, the path to education was closed.
Only with the advent of the first schools on the European model did it become necessary to pick up a word meaning free time from school. And it was not a vacation at all. This concept entered the Russian language only at the end of the 19th century, and earlier the annual “holidays” of schoolchildren were called vacancies, that is, the word vacances borrowed from French.
In the old days, as now, students of various educational institutions received rest from classes several times a year. But since summer vacancies were longer, it was required to find a separate word for them. It was then that they remembered the Roman "vacation", for convenience, giving the term plural, as with the "vacancies" already familiar at that time.
As you can see, the interpretation of the word "vacation" is rather complicated, but very interesting. In such a familiar name for us, ancient myths, names of stars and the first ideas of people about the influence of celestial bodies on the earth's climate intertwined.