Planet Saturn is known in many names across the globe - Kronos in greek, Kevan / Kaivan in Persia and "Sanischara" in India. In some cultures Planet Saturn was considered as one of the chief deities and in India it has been one of the devata in Navagraha!.
The actual Indian name for Saturn is Sanischara which became Saniswara and in short Sani / Shani. Char means move / movement, Chara means mover and Sani means slow and is named based on the definition Śanayē Kramati Saḥ (शनये क्रमति सः), the one who moves slowly. The slowest mover among the 9 Grahas is Saturn as per vedic astrologer and hence this name was given.
As you are aware Vedic astrology does not consider Pluto, Uranus and Neptune as planets affecting our lives. I shall write the reason behind this later but would like to highlight that the vedic astrologers were very well aware of these planets but did not take it into consideration for ASTROLOGY since they are too weak and far away to affect our lives through their radiation.
The table above gives approximate distance from Sun, the circumference of the orbit and the speed of travel for 6 major planets. Saturn takes 30 years to complete one revolution at an approximate speed of 9.95 Kms / second. Jupiter takes 12 years to complete one revolution at a speed of 13.27 Kms/second. All readings are approximate.
Since saturn takes 30 years for one full round the sun, so in each house it stays for 2.5 years. So for 12 zodiacs 30 years. Sade Saath / 7.5 years of Sani / ஏழரை நாட்டு சனி refers to transit of Sani in your Rasi (where the moon is at the time of your birth) the previous and next rasi. In short if your Rasi (moon sign and not sun sign) is Virgo then Sani in Leo, Virgo and Libra is the Saade Saath period for you.
You may note that the duration of one day decreases suggesting the planets rotate around their axis faster as they move away from sun and Venus is the only planet whose day is longer than the year. So, you get 12 months in a day in Venus, Yeah 12 salaries in a day for the salaried class and monthly, quarterly, Half yearly and annual sales reviews all in a day :)
You also note that Mars is the closest to Earth in terms of duration of a day and hence this may be one of the reasons as to why NASA is looking for possibility of life support in Mars.
But the point i wanted to highlight is the Indian / Vedic nomenclature contains the very reason as to why something is named so.
Bhoogol means study earth / geography, Bhoo means earth and "Gol" means round / circle suggests that Indians knew that the earth was round ages back.
Brahmaanda means universe, Brahm - Very big and Anda means Egg. So universe is a huge egg suggesting it is elliptical in shape.
Let me conclude that many languages and ancient civilizations are rich and have named things based on a reason or meaning lets be inquisitive to understand the roots / meaning behind a name.