Valentine's Day, the 14th of February, on which young people of both sexes were wont (the custom seems gradually dying out) to send love-missives to one another; it is uncertain who the Valentine was that is associated with the day, or whether it was with any of the name.
Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)
Valentine, Basil * Valentinian I.