Philter \FIL-ter\ , noun;
1. A magic potion for any purpose
2. A potion, charm, or drug supposed to cause the person taking it to fall in love, usually with some specific person
According to Etymonline.com:
Philter (alternatively philtre) meaning "love potion" dates to the 1580's and comes from Middle French philtre. French philtre dates to the 1560's and derives from Latin philtrum which comes from Greek philtron. Philtron is a combination of philein ("to love" from philos "loving") + -tron (instrumental suffix) so its literal meaning is "to make oneself beloved" but it was actually used to mean "love charm"
*Today's word and the first definition were both taken from Dictionary.com's 'Word of the Day' for Saturday, December 11