Sabbath: a God-appointed time of complete stopping, set apart as holy
At its root this word means stopping, not relaxing. It comes from the everyday verb for bringing something to an end, and when the Bible turns that verb into a noun it names a stretch of time on which all ordinary work is laid down by command and the time itself is treated as holy. The most familiar form is the seventh day of every week, but the same word stretches outward to a whole seventh year of stopping for the farmland, to a span of seven days counted as a single unit, and to certain solemn days of total rest that are not the weekly seventh day. What holds all of these together is one idea: a deliberate, appointed cessation that belongs to God.
The seventh-day Sabbath is the heart of the word and the source of the rest. The Bible grounds it two ways that the other books never fully blend. In one telling it reaches back to the world's making, when God himself finished and stopped on the seventh day, so the day is woven into the order of things. In another it reaches back to slavery in Egypt, so the day is a weekly act of mercy that hands rest to servants, foreigners, and even work animals. Either way the day is presented as a gift and a sign, a standing mark of belonging between God and his people.
The other senses are this same stopping carried into larger and smaller rhythms. The land gets its own seventh-year Sabbath, when fields are left unworked. Seven of those days strung together make a Sabbath in the sense of a week, the unit counted off toward the festival of weeks. And the gravest holy days, above all the Day of Atonement, are called a Sabbath of complete stopping even though they fall on no fixed weekday. The reader should hear cessation first in every case, and let the context say whether it is a day, a year, a week, or a solemn feast.