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