Some say that the term “caddie” was originally coined by Mary Queen of Scots in 1552. Here’s the story: She was the first female to play the game of golf. When she was living in France during her youth, it was traditional for French military cadets to carry the clubs of royalty. The cadets carrying golf clubs actually came to be called caddies due to the French language. The word cadet in French is pronounced “ca-dee,” thus the term. The word traveled to Scotland when Mary returned there in 1561.
The first problem with this is that the French word is NOT pronounced Cadee, but more like something between Caday and Cadeh. Another is the claim that she was the first woman to play golf. Possible but highly unlikely.
However, according to the Oxford English Dictionary, caddy or caddie does come from the word “cadet,” from the French, meaning a younger son or younger brother, or the junior branch of the family. The first known written use was 1610, when it meant, “a gentleman who entered the army without a commission to learn the military profession and find a career for himself (as was regularly done by the younger sons of French nobility before the French Revolution).”
Caddie definition #1 from the Scots, 1730, “lad or man who waits about on the lookout for chance employment as a messenger, odd-job man, etc.” 1817 “a caddy came with a large parcel to Mrs. Hogan’s house.”
Definition #2, 1634, from the Scots “a young gentleman latelie come from France, pransing . . . with his short skarlet cloake and his long caudie rapier.” Or 1776 “with his sword by his side like a cadie.”
1908 #3 caddy: verb, to act as caddy for a golfer
While we can’t know whether Mary Queen of Scots was really the first woman to play golf, the word origin part of the story seems largely true.