The first thing to know about the etymology of thanksgiving is that it’s all in your mind. The English verb thank is thought to be rooted in an ancient word meaning “think.”
Thank goes back to an Old English verb meaning to thank, to give thanks, or to reward. The Online Etymology Dictionary traces this, in turn, to a Proto-
Indo-European tong meaning “to think, feel.”
Proto-Indo-European roots are words or parts of words that linguists believe are ancestors of words in today’s languages. The quest for these roots is a little bit like the way paleontologists figure out what dinosaurs must have looked like, except that the linguists don’t have actual bones to work with.
At Thanksgiving we are grateful for our blessings, and that word comes from the Latin-derived vocabulary of English.
The original word was simply grate, meaning “pleasing to the mind,” but also “full of gratitude, disposed to repay favors bestowed.” The (redundant) ful was tacked on later. The Online Etymology Dictionary quotes a source calling this a “most unusual formation,” and wonders, “Is there another case where English uses -ful to make an adjective from an adjective?”
The Latin gratia was a semantic cornucopia of positive meanings: “favor, esteem, regard; pleasing quality, good will, gratitude.” It led to grace, as an English verb meaning “to thank” (1200), later “to show favor” (mid-15th century), and then “to lend or add grace to something,” as in “grace us with your presence,” as the dictionary further explains. Hence the grace notes of music, meant to add a little something extra, a “favor” or bonus.
Gratia is the source of grazie and gracias, the usual way of saying “thanks” in Italian and Spanish, respectively.
French has the preposition grâce à, meaning “through” or “by means of.” It’s equivalent to the English “thanks to,” often used with distinctly ungrateful irony: “Thanks to the rush-hour traffic, we missed curtain time.”
But if you know even five words of French, you know that the unironic “thank you” in that language comes not from gratia, but rather is merci.
That French word can be traced back to the Latin merx, meaning wares or merchandise, a root that shows up in English in commerce, merchant, and even market.
When the French merci slipped over into English, though, it seems to have lost the transactional sense. Somewhat loftier meanings were attached to it, according to the Oxford English Dictionary (OED): “pity, (secular or divine) grace, discretionary judgement, mercy.”
Modern French has settled on merci as the ordinary word for “thanks.” But the English meaning evolved along a different path, as in this OED definition of a sense going back to around 1225: “Clemency and compassion shown to a person who is in a position of powerlessness or subjection, or to a person with no right or claim to receive kindness.”
May you have a thoughtfully thankful holiday!