Valentine /(?)/

Val·en·tine

Valentine

n.
  1. A sweetheart chosen on St. Valentine's Day.
  2. A letter containing professions of love, or a missive of a sentimental, comic, or burlesque character, sent on St. Valentine's Day.

Phrases & Compounds
St. Valentine's Day
a day sacred to St. Valentine; the 14th of February. It was a very old notion, alluded to by Shakespeare, that on this day birds begin to mate. Hence, perhaps, arose the custom of sending love tokens at that time.