sabbath [OE] The sabbath is the day of rest—Saturday for Jews, Sunday for Christians. The Hebrew word sabat, ‘to rest’, is the ultimate source. The Law of Moses dictated that every seventh year should be observed as a ‘sabbath’, during which the land lay fallow. In the late 19th century US universities extended the idea of this sabbatical year to give professors and other academic staff every seventh year free to research or travel. Nowadays a sabbatical may come at other intervals of time, and members of other occupations also use the term for paid leave for professional development.