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]

Easton's 1897 Bible Dictionary:

Phylacteries
   (Gr. phulakteria; i.e., "defences" or "protections"), called by
   modern Jews tephillin (i.e., "prayers") are mentioned only in
   Matt. 23:5. They consisted of strips of parchment on which were
   inscribed these four texts: (1.) Ex. 13:1-10; (2.) 11-16; (3.)
   Deut. 6:4-9; (4.) 11:18-21, and which were enclosed in a square
   leather case, on one side of which was inscribed the Hebrew
   letter shin, to which the rabbis attached some significance.
   This case was fastened by certain straps to the forehead just
   between the eyes. The "making broad the phylacteries" refers to
   the enlarging of the case so as to make it conspicuous. (See FRONTLETS.)

     Another form of the phylactery consisted of two rolls of
   parchment, on which the same texts were written, enclosed in a
   case of black calfskin. This was worn on the left arm near the
   elbow, to which it was bound by a thong. It was called the
   "Tephillah on the arm."


Hitchcock's Bible Names Dictionary (late 1800's):

Phylacteries, things to be especially observed