Because of its long practice of borrowing words from other languages, English has acquired a huge stock of doublets, pairs of words that began as the same word, but over time have changed in form and in meaning.
Sometimes the kinship between doublets, such as potion and poison, are fairly obvious. With others, such as tradition and treason, not so much.
Both potion and poison derive from Latin potionem, “a drink,” from the Latin verb potare “to drink.” Both words came into English from two Old French words: pocion and puison, both of which meant “drink.”
A potion is a drink prepared for some specialized purpose, magical or medicinal. A famous love potion is the one Iseult’s mother prepared to be drunk by her daughter on her wedding night with King Mark. Unfortunately, Iseult found the potion on the voyage to meet her new husband and unwittingly shared it with Mark’s handsome young nephew Tristan. Oops.
A poison is a potion prepared with the intention of killing the person who drinks it.
The words tradition and treason both come from the Latin traditionem, “a handing over; delivery, surrender.” They entered English from Old French traison, a form influenced by Old French trair “to betray, and tradicion, a form closer to its Latin original.
Treason is the act of betraying one’s king or country, often by handing over something, for example the keys to the city, or sensitive information. Tradition is the “handing down” of something from generation to generation.
More doublets to come.