I confused these the other day. Fortunately only verbally.
phy•lac•ter•y (f -l k t -r )
n. pl. phy•lac•ter•ies
1. Judaism Either of two small leather boxes, each containing strips of parchment inscribed with quotations from the Hebrew Scriptures, one of which is strapped to the forehead and the other to the left arm; traditionally worn by Jewish men during morning worship, except on the Sabbath and holidays.
a. An amulet.
b. A reminder.
pro•phy•lac•tic (pr f -l k t k, pr f -)
Acting to defend against or prevent something, especially disease; protective.
1. A prophylactic agent, device, or measure, such as a vaccine or drug.
2. A contraceptive device, especially a condom.