sabbatical (adj.)

1640s, "of or suitable for the Sabbath," from Latin sabbaticus, from Greek sabbatikos "of the Sabbath" (see Sabbath). Noun meaning "a year's absence granted to researchers" (originally one year in seven, to university professors) is from 1934, short for sabbatical year, etc., first recorded 1886 (the thing itself is attested from 1880, at Harvard), related to sabbatical year (1590s) in Mosaic law, the seventh year, in which land was to remain untilled and debtors and slaves released.