The Collaborative International Dictionary of English v.0.48:

Phylactery \Phy*lac"ter*y\, n.; pl. Phylacteries. [OE.
   filateri, OF. filatire, filatiere, F. phylact[`e]re, L.
   phylacterium, Gr. fylakth`rion, fr. fylakth`r a watcher,
   guard, fyla`ssein to watch, guard. Cf. Philatory.]
   1. Any charm or amulet worn as a preservative from danger or
      disease.
      [1913 Webster]

   2. A small square box, made either of parchment or of black
      calfskin, containing slips of parchment or vellum on which
      are written the scriptural passages Exodus xiii. 2-10, and
      11-17, Deut. vi. 4-9, 13-22. They are worn by Jews on the
      head and left arm, on week-day mornings, during the time
      of prayer. --Schaff-Herzog Encyc.
      [1913 Webster]

   3. Among the primitive Christians, a case in which the relics
      of the dead were inclosed.
      [1913 Webster]

WordNet (r) 3.0 (2006):

phylactery
    n 1: (Judaism) either of two small leather cases containing
         texts from the Hebrew Scriptures (known collectively as
         tefillin); traditionally worn (on the forehead and the left
         arm) by Jewish men during morning prayer [syn:
         phylactery, tefillin]

Moby Thesaurus II by Grady Ward, 1.0:

80 Moby Thesaurus words for "phylactery":
   Agnus Dei, Holy Grail, Host, Pieta, Sanctus bell, Sangraal, amulet,
   ark, asperger, asperges, aspergillum, bambino, beadroll, beads,
   candle, censer, chaplet, charm, ciborium, cross, crucifix, cruet,
   eucharistial, fetish, fylfot, gammadion, good-luck charm,
   holy cross, holy water, holy-water sprinkler, hoodoo, icon,
   incensory, juju, love charm, luck, lucky bean, lucky piece,
   madstone, mascot, matzo, menorah, mezuzah, mikvah, monstrance,
   mumbo jumbo, obeah, osculatory, ostensorium, paschal candle, pax,
   periapt, philter, phylacteries, prayer shawl, prayer wheel, pyx,
   relics, rood, rosary, sacramental, sacred relics, sacring bell,
   scarab, scarabaeus, scarabee, shofar, sudarium, sukkah, swastika,
   tabernacle, talisman, tallith, thurible, urceole, veronica,
   vigil light, voodoo, votive candle, whammy