🔼The name Sabbath in the Bible
Sabbath is the name of the last day of the week (Exodus 20:8). The Oxford Companion to the Bible notes that only this day is named while the rest of the days of the week are only numbered. In the Greek New Testament, the name Sabbath is spelled σαββατον, sabbaton.
The Sabbath probably had several separate functions. The Sabbath is generally considered to have as primary function to provide people with some respite, but that's obviously too simple an explanation. Nature doesn't have Sabbaths and only lifestyles that allows planning and storing allows interruption of one's daily routine (it would exclude hunter-gatherers and herd-following nomads). A Sabbath is not for rest in general, it is rest from the commercial cycle, and although there is nothing wrong with commerce per se, commerce might prove to be quite intoxicating if one doesn't distantiate from it every seventh day (or every seventh year in case of a Sabbath Year; also see our article on Jubilee).
On the Sabbath, people had the opportunity to converse with others and take strolls or observe creation. It's not explicitly stated, but it would come as no surprise if most collective ideas, joys and offspring were conceived of on Sabbaths.
🔼Etymology of the name Sabbath
The name Sabbath has to do with the verb שבת (shabat), meaning to cease or to rest:
The invention of the Sabbath, which marks the week, is a bit of a mystery. All other units of time, from year to month to day, even hours, have their roots in the celestial cycles but the week doesn't. Some scholars have tried to tie the Hebrew Sabbath to significant days in other cultures but no theory entirely satisfies. The week seems to be a Hebrew invention, and we have no idea why they did it or why it became such a hit all over the world.
It should also be noted that although the Sabbath (the Rest) is celebrated on one specific day of the week, it really says something about the week as a whole. The word shabbat indicates where one week turns into the next and the Oxford Companion's note that the Sabbath is the only day that is named may be explained by the idea that any collection is defined by its borders. After all, we comfortably speak of "the end of the road," but never about "one step before the end of the road". The "end of the road" says something about the whole road, and very little about the actual location where the road stops.
The name Sabbath means Rest, Severance or Cessation.