Wordnet 3.0
NOUN (1)
1. 
 one who observes Saturday as the Sabbath (as in Judaism); 
ADJECTIVE (1)
1. 
 pertaining to the Sabbath and its observance; 
The Collaborative International Dictionary of English v.0.48:
Sabbatarian \Sab`ba*ta"ri*an\, n. [L. Sabbatarius: cf. F.
   sabbataire. See Sabbath.]
   1. One who regards and keeps the seventh day of the week as
      holy, agreeably to the letter of the fourth commandment in
      the Decalogue.
      [1913 Webster]
   Note: There were Christians in the early church who held this
         opinion, and certain Christians, esp. the Seventh-day
         Baptists, hold it now.
         [1913 Webster]
   2. A strict observer of the Sabbath.
      [1913 Webster]
The Collaborative International Dictionary of English v.0.48:
Sabbatarian \Sab`ba*ta"ri*an\, a.
   Of or pertaining to the Sabbath, or the tenets of
   Sabbatarians.
   [1913 Webster]
WordNet (r) 3.0 (2006):
Sabbatarian
    adj 1: pertaining to the Sabbath and its observance
    n 1: one who observes Saturday as the Sabbath (as in Judaism)
Moby Thesaurus II by Grady Ward, 1.0:
49 Moby Thesaurus words for "Sabbatarian":
   Albigensian, Catharist, Franciscan, High-Churchist, Trappist,
   Waldensian, abstainer, abstinent, anchorite, anchoritic, ascetic,
   austere, bhikshu, bigoted, creedbound, dervish, dogmatic, eremitic,
   evangelical, fakir, flagellant, formalist, formularist, formulist,
   fundamentalist, hermit, hidebound, hyperorthodox, literalist,
   literalistic, liturgist, mendicant, precisianist, precisianistic,
   purist, puristic, puritan, puritanical, rigoristic, ritualist,
   sacramentarian, sannyasi, self-denying, staunch, straitlaced,
   strict, wedded to poverty, yogi, yogin