The Collaborative International Dictionary of English v.0.48:

Puritan \Pu"ri*tan\, n. [From Purity.]
   1. (Eccl. Hist.) One who, in the time of Queen Elizabeth and
      the first two Stuarts, opposed traditional and formal
      usages, and advocated simpler forms of faith and worship
      than those established by law; -- originally, a term of
      reproach. The Puritans formed the bulk of the early
      population of New England.
      [1913 Webster]

   Note: The Puritans were afterward distinguished as Political
         Puritans, Doctrinal Puritans, and Puritans in
         Discipline. --Hume.
         [1913 Webster]

   2. One who is scrupulous and strict in his religious life; --
      often used reproachfully or in contempt; one who has
      overstrict notions.
      [1913 Webster]

            She would make a puritan of the devil. --Shak.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Puritan \Pu"ri*tan\, a.
   Of or pertaining to the Puritans; resembling, or
   characteristic of, the Puritans.
   [1913 Webster] Puritanic

WordNet (r) 3.0 (2006):

Puritan
    n 1: a member of a group of English Protestants who in the 16th
         and 17th centuries thought that the Protestant Reformation
         under Elizabeth was incomplete and advocated the
         simplification and regulation of forms of worship
    2: someone who adheres to strict religious principles; someone
       opposed to sensual pleasures
    3: a person excessively concerned about propriety and decorum
       [syn: prude, puritan]

Moby Thesaurus II by Grady Ward, 1.0:

84 Moby Thesaurus words for "puritan":
   Albigensian, Catharist, Franciscan, Grundy, Sabbatarian, Trappist,
   Victorian, Waldensian, abstainer, anchorite, ascetic, austere,
   bhikshu, bigoted, bluenose, dervish, disapproving, dour, fakir,
   fanatic, firm, flagellant, fundamentalist, goody-goody, hard,
   hard-line, hard-nosed, hermit, hidebound, impliable, inexorable,
   inflexible, intolerant, iron, ironbound, ironclad, ironhanded,
   mendicant, mid-Victorian, moralistic, muscle-bound, narrow-minded,
   obdurate, obstinate, old maid, orthodox, pietist, pietistic, prig,
   prim, procrustean, proper, prude, prudish, purist, puristic,
   puritanic, puritanical, relentless, religionist, rigid, rigorist,
   rigoristic, rigorous, rockbound, sannyasi, severe, stern, stiff,
   stiff-necked, straightlaced, strait-laced, straitlaced, strict,
   stubborn, stuffy, unbending, uncompromising, unrelenting,
   unyielding, uptight, yogi, yogin, zealot