The Collaborative International Dictionary of English v.0.48:

Movable \Mov"a*ble\, a. [Cf. OF. movable. See Move.]
   1. Capable of being moved, lifted, carried, drawn, turned, or
      conveyed, or in any way made to change place or posture;
      susceptible of motion; not fixed or stationary; as, a
      movable steam engine. [Also spelled moveable.]

   Syn: transferable, transferrable, transportable.
        [1913 Webster]

   2. Changing from one time to another; as, movable feasts, i.
      e., church festivals, the date of which varies from year
      to year.
      [1913 Webster]

   Movable letter (Heb. Gram.), a letter that is pronounced,
      as opposed to one that is quiescent.

   Movable feast (Ecclesiastical), a holy day that changes
      date, depending on the lunar cycle. An example of such a
      day is Easter.
      [1913 Webster +PJC]

The Collaborative International Dictionary of English v.0.48:

Easter \Eas"ter\ ([=e]s"t[~e]r), n. [AS. e['a]ster, e['a]stran,
   paschal feast, Easter; akin to G. ostern; fr. AS. E['a]stre,
   a goddess of light or spring, in honor of whom a festival was
   celebrated in April; whence this month was called in AS.
   E['a]sterm[=o]na[eth]. From the root of E. east. See East.]
   1. An annual church festival commemorating Christ's
      resurrection, and occurring on Sunday, the second day
      after Good Friday. It corresponds to the pascha or
      passover of the Jews, and most nations still give it this
      name under the various forms of pascha, pasque,
      p[^a]que, or pask.
      [1913 Webster]

   2. The day on which the festival is observed; Easter day.
      [1913 Webster]

   Note: Easter is used either adjectively or as the first
         element of a compound; as, Easter day or Easter-day,
         Easter Sunday, Easter week, Easter gifts, Easter eggs.
         [1913 Webster]

               Sundays by thee more glorious break,
               An Easter day in every week.       --Keble.
         [1913 Webster]

   Note: Easter day, on which the rest of the movable feasts
         depend, is always the first Sunday after the fourteenth
         day of the calendar moon which (fourteenth day) falls
         on, or next after, the 21st of March, according to the
         rules laid down for the construction of the calendar;
         so that if the fourteenth day happen on a Sunday,
         Easter day is the Sunday after. --Eng. Cyc.
         [1913 Webster]

   Easter dues (Ch. of Eng.), money due to the clergy at
      Easter, formerly paid in communication of the tithe for
      personal labor and subject to exaction. For Easter dues,
      Easter offerings, voluntary gifts, have been substituted.


   Easter egg.
      (a) A painted or colored egg used as a present at Easter.
      (b) An imitation of an egg, in sugar or some fine
          material, sometimes made to serve as a box for jewelry
          or the like, used as an Easter present.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Easter \East"er\, v. i. (Naut.)
   To veer to the east; -- said of the wind. --Russell.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Easter
    n 1: a Christian celebration of the Resurrection of Christ;
         celebrated on the Sunday following the first full moon
         after the vernal equinox
    2: a wind from the east [syn: east wind, easter, easterly]

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "Easter":
   Advent, Allhallowmas, Allhallows, Allhallowtide, Annunciation,
   Annunciation Day, Ascension Day, Ash Wednesday, Candlemas,
   Candlemas Day, Carnival, Christmas, Corpus Christi, Easter Monday,
   Easter Saturday, Easter Sunday, Eastertide, Ember days, Epiphany,
   Good Friday, Halloween, Hallowmas, Holy Thursday, Holy Week,
   Lady Day, Lammas, Lammas Day, Lammastide, Lent, Lententide,
   Mardi Gras, Martinmas, Maundy Thursday, Michaelmas, Michaelmas Day,
   Michaelmastide, Palm Sunday, Pancake Day, Passion Week, Pentecost,
   Quadragesima, Quadragesima Sunday, Septuagesima, Shrove Tuesday,
   Trinity Sunday, Twelfth-day, Twelfth-tide, Whit-Tuesday,
   White Sunday, Whitmonday, Whitsun, Whitsunday, Whitsuntide,
   Whitweek



Easton's 1897 Bible Dictionary:

Easter
   originally a Saxon word (Eostre), denoting a goddess of the
   Saxons, in honour of whom sacrifices were offered about the time
   of the Passover. Hence the name came to be given to the festival
   of the Resurrection of Christ, which occured at the time of the
   Passover. In the early English versions this word was frequently
   used as the translation of the Greek pascha (the Passover). When
   the Authorized Version (1611) was formed, the word "passover"
   was used in all passages in which this word pascha occurred,
   except in Act 12:4. In the Revised Version the proper word,
   "passover," is always used.