Most people know that Valentine's Day is named after St. Valentine, but the rest isn't discussed too often. The Latinized version of the name is Valentinus, the root being valentia, or "strong" (also the etymon of the chemical term valence). Valentia is the present participle of the verb valere ("to be strong") and that, through Proto-Italic waleo, eventually derives from Proto-Indo-European hwelh, which could either mean "to rule" or "to be strong". As you can see, the saint's name really has nothing to do with love, and neither did the saint himself... until the High Middle Ages, that is, when it became a custom in English and French courts to choose a sweetheart around that time of year when birds choose their mates. By the 1450s, the concepts of Valentine's Day and love were inextricably linked, and we've never looked back.
Adam Aleksic, a freshman studying linguistics at Harvard University, has been described as the internet's sixth most famous etymologist. He has disturbing interests in words, vexillology, geography, board games, limericks, and law, and he loves writing about himself in the third person.
The Etymology Nerd