The Collaborative International Dictionary of English v.0.48:

Sabbath \Sab"bath\, n. [OE. sabat, sabbat, F. sabbat, L.
   sabbatum, Gr. sa`bbaton, fr. Heb. shabb[=a]th, fr. sh[=a]bath
   to rest from labor. Cf. Sabbat.]
   1. A season or day of rest; one day in seven appointed for
      rest or worship, the observance of which was enjoined upon
      the Jews in the Decalogue, and has been continued by the
      Christian church with a transference of the day observed
      from the last to the first day of the week, which is
      called also Lord's Day.
      [1913 Webster]

            Remember the sabbath day, to keep it holy. --Ex. xx.
                                                  8.
      [1913 Webster]

   2. The seventh year, observed among the Israelites as one of
      rest and festival. --Lev. xxv. 4.
      [1913 Webster]

   3. Fig.: A time of rest or repose; intermission of pain,
      effort, sorrow, or the like.
      [1913 Webster]

            Peaceful sleep out the sabbath of the tomb. --Pope.
      [1913 Webster]

   Sabbath breaker, one who violates the law of the Sabbath.


   Sabbath breaking, the violation of the law of the Sabbath.


   Sabbath-day's journey, a distance of about a mile, which,
      under Rabbinical law, the Jews were allowed to travel on
      the Sabbath.
      [1913 Webster]

   Syn: Sabbath, Sunday.

   Usage: Sabbath is not strictly synonymous with Sunday.
          Sabbath denotes the institution; Sunday is the name of
          the first day of the week. The Sabbath of the Jews is
          on Saturday, and the Sabbath of most Christians on
          Sunday. In New England, the first day of the week has
          been called "the Sabbath," to mark it as holy time;
          Sunday is the word more commonly used, at present, in
          all parts of the United States, as it is in England.
          "So if we will be the children of our heavenly Father,
          we must be careful to keep the Christian Sabbath day,
          which is the Sunday." --Homilies.
          [1913 Webster]

WordNet (r) 3.0 (2006):

Sabbath
    n 1: a day of rest and worship: Sunday for most Christians;
         Saturday for the Jews and a few Christians; Friday for
         Muslims

Easton's 1897 Bible Dictionary:

Sabbath
   (Heb. verb shabbath, meaning "to rest from labour"), the day of
   rest. It is first mentioned as having been instituted in
   Paradise, when man was in innocence (Gen. 2:2). "The sabbath was
   made for man," as a day of rest and refreshment for the body and
   of blessing to the soul.

     It is next referred to in connection with the gift of manna to
   the children of Israel in the wilderness (Ex. 16:23); and
   afterwards, when the law was given from Sinai (20:11), the
   people were solemnly charged to "remember the sabbath day, to
   keep it holy." Thus it is spoken of as an institution already
   existing.

     In the Mosaic law strict regulations were laid down regarding
   its observance (Ex. 35:2, 3; Lev. 23:3; 26:34). These were
   peculiar to that dispensation.

     In the subsequent history of the Jews frequent references are
   made to the sanctity of the Sabbath (Isa. 56:2, 4, 6, 7; 58:13,
   14; Jer. 17:20-22; Neh. 13:19). In later times they perverted
   the Sabbath by their traditions. Our Lord rescued it from their
   perversions, and recalled to them its true nature and intent
   (Matt. 12:10-13; Mark 2:27; Luke 13:10-17).

     The Sabbath, originally instituted for man at his creation, is
   of permanent and universal obligation. The physical necessities
   of man require a Sabbath of rest. He is so constituted that his
   bodily welfare needs at least one day in seven for rest from
   ordinary labour. Experience also proves that the moral and
   spiritual necessities of men also demand a Sabbath of rest. "I
   am more and more sure by experience that the reason for the
   observance of the Sabbath lies deep in the everlasting
   necessities of human nature, and that as long as man is man the
   blessedness of keeping it, not as a day of rest only, but as a
   day of spiritual rest, will never be annulled. I certainly do
   feel by experience the eternal obligation, because of the
   eternal necessity, of the Sabbath. The soul withers without it.
   It thrives in proportion to its observance. The Sabbath was made
   for man. God made it for men in a certain spiritual state
   because they needed it. The need, therefore, is deeply hidden in
   human nature. He who can dispense with it must be holy and
   spiritual indeed. And he who, still unholy and unspiritual,
   would yet dispense with it is a man that would fain be wiser
   than his Maker" (F. W. Robertson).

     The ancient Babylonian calendar, as seen from recently
   recovered inscriptions on the bricks among the ruins of the
   royal palace, was based on the division of time into weeks of
   seven days. The Sabbath is in these inscriptions designated
   Sabattu, and defined as "a day of rest for the heart" and "a day
   of completion of labour."

     The change of the day. Originally at creation the seventh day
   of the week was set apart and consecrated as the Sabbath. The
   first day of the week is now observed as the Sabbath. Has God
   authorized this change? There is an obvious distinction between
   the Sabbath as an institution and the particular day set apart
   for its observance. The question, therefore, as to the change of
   the day in no way affects the perpetual obligation of the
   Sabbath as an institution. Change of the day or no change, the
   Sabbath remains as a sacred institution the same. It cannot be
   abrogated.

     If any change of the day has been made, it must have been by
   Christ or by his authority. Christ has a right to make such a
   change (Mark 2:23-28). As Creator, Christ was the original Lord
   of the Sabbath (John 1:3; Heb. 1:10). It was originally a
   memorial of creation. A work vastly greater than that of
   creation has now been accomplished by him, the work of
   redemption. We would naturally expect just such a change as
   would make the Sabbath a memorial of that greater work.

     True, we can give no text authorizing the change in so many
   words. We have no express law declaring the change. But there
   are evidences of another kind. We know for a fact that the first
   day of the week has been observed from apostolic times, and the
   necessary conclusion is, that it was observed by the apostles
   and their immediate disciples. This, we may be sure, they never
   would have done without the permission or the authority of their
   Lord.

     After his resurrection, which took place on the first day of
   the week (Matt. 28:1; Mark 16:2; Luke 24:1; John 20:1), we never
   find Christ meeting with his disciples on the seventh day. But
   he specially honoured the first day by manifesting himself to
   them on four separate occasions (Matt. 28:9; Luke 24:34, 18-33;
   John 20:19-23). Again, on the next first day of the week, Jesus
   appeared to his disciples (John 20:26).

     Some have calculated that Christ's ascension took place on the
   first day of the week. And there can be no doubt that the
   descent of the Holy Ghost at Pentecost was on that day (Acts
   2:1). Thus Christ appears as instituting a new day to be
   observed by his people as the Sabbath, a day to be henceforth
   known amongst them as the "Lord's day." The observance of this
   "Lord's day" as the Sabbath was the general custom of the
   primitive churches, and must have had apostolic sanction (comp.
   Acts 20:3-7; 1 Cor. 16:1, 2) and authority, and so the sanction
   and authority of Jesus Christ.

     The words "at her sabbaths" (Lam. 1:7, A.V.) ought probably to
   be, as in the Revised Version, "at her desolations."


Bouvier's Law Dictionary, Revised 6th Ed (1856):

SABBATH. The same as Sunday. (q.v.)



The Devil's Dictionary (1881-1906):

SABBATH, n.  A weekly festival having its origin in the fact that God
made the world in six days and was arrested on the seventh.  Among the
Jews observance of the day was enforced by a Commandment of which this
is the Christian version:  "Remember the seventh day to make thy
neighbor keep it wholly."  To the Creator it seemed fit and expedient
that the Sabbath should be the last day of the week, but the Early
Fathers of the Church held other views.  So great is the sanctity of
the day that even where the Lord holds a doubtful and precarious
jurisdiction over those who go down to (and down into) the sea it is
reverently recognized, as is manifest in the following deep-water
version of the Fourth Commandment:

    Six days shalt thou labor and do all thou art able,
    And on the seventh holystone the deck and scrape the cable.

    Decks are no longer holystoned, but the cable still supplies the
captain with opportunity to attest a pious respect for the divine
ordinance.