Sabbatical

Sabbatical (pronounced suh-bat-i-kuhl)

(1) Of or pertaining or appropriate to the Sabbath (initial uppercase).

(2) Of or relating to a sabbatical year which can be formal or informal (initial lowercase).

(3) Bringing a period of rest (initial lowercase).

(4) As sabbatical leave, an extended period of leave from one's customary work (initial lowercase).

(5) In academia, denoting a post that renders the holder eligible for such leave (initial lowercase).

1605–1615: From the Ancient Greek sabbatikós (sábbat(on)), the construct being Sabbath + -ikos or -ic).  Sabbath is from the Middle English sabat, sabbat & sabath, from the Old English Sabat, from the Old French sabat & sabbat and its etymon Latin sabbatum, from the Ancient Greek σάββατον (sábbaton) (Sabbath), from the Hebrew שַׁבָּת‎ (shabát) (Sabbath).  That the spelling ended -th was probably influenced by the traditional transliteration of the Hebrew as shabbāth, being attested since the fourteenth century and in widespread use since the sixteenth.  sabbatical is a noun & adjective and sabbatically is an adverb (only in the context of the sabbath); the noun plural is sabbaticals.  Some sources list the noun sabbaticalness but it's treated by others as non-standard.  

The Middle English suffix –ik, like the Old French –ique and the –icus is from the primitive Indo-European -ikos, formed with the i-stem suffix -i and the adjectival suffix -ko.  Related are the Ancient Greek -ικός (-ikós), the Sanskrit श (śa), क (ka) and the Old Church Slavonic -ъкъ (-ŭkŭ); doublet of -y.  The suffix on noun stems carried the meaning “characteristic of, like, pertaining to” and on adjectival stems it acted emphatically.  The –al suffix of the adjectival (and most familiar) form is from the Latin -ālis, or the French, Middle French and Old French –el & -al  It’s thought likely the Latin suffix was formed from the Etruscan genitive suffix -l (as in Etruscan ati (mother) / atial (mother's)) + adjectival suffix -is (as in fortis, dēbilis, etc).  The origins of the sabbatical lie in the Biblical practice of shmita, a practice of agriculture which defined (Leviticus 25) when productive lands must lie fallow.  It stipulated the Jews in the Land of Israel must take a year-long break from working the fields every seven years.  The practice still exists in some types of modern agriculture although typically not on seven year-cycles

Lindsay Lohan enjoying a sabbatical, Los Angeles, August 2012.

Until recent decades, the sabbatical was most associated with a period of leave granted to senior tenured academics, traditionally every seven years.  Until the re-structuring of universities in the 1980s, the sabbatical was essentially the private right of the professor concerned and could be used for composition, calculation or convenience.  By convention, it was thought bad form to ask a professor how he spent his sabbatical; politeness demanded one had to wait for him to raise the matter.  Of late however, institutions offer fewer sabbaticals and those which do have tended increasingly to create structured programmes, sometimes exchange schemes with other universities and it's not unknown for institutions to expect some tangible outcome from a sabbatical.  The word has also entered commerce and some corporations offer (and sometimes compel) extended periods of leave under various terms and conditions.  Popular reasons for these corporate "holidays" include (1) being under investigation for sexual harassment, (2) being charged with some crime, (3) being suspected of insider trading and (4) being someone the corporation would like for some reason to sack but fear exists about the consequences.