Chef is a late French borrowing, and it says so in the way it is pronounced: the ch is a sh sound, not the ch of church. That difference is a dating tool. English took chief from Old French around 1300, when French still said the ch as ch; it took chef from French again in 1842, by which time French had softened it. Same word, borrowed twice, five centuries apart, with the pronunciation of each borrowing frozen at the moment it arrived.
The French word is short for chef de cuisine, "head of the kitchen," and behind it is Old French chief, "leader, head," from Latin caput, "head." So a chef is simply a chief — the boss of the kitchen — and English speakers who use both words rarely notice they are the same. The pair sits alongside catch and chase, warden and guardian: the same root, borrowed at different dates, kept apart by the sound it happened to have on arrival.
chef (n.) "head cook," 1842, from French chef , short for chef de cuisine , literally "head of the kitchen," from Old French chief "leader, ruler, head" (see chief (n.)). also from 1842
chef came in through Later and wider borrowings, and its spelling follows that family's conventions.
How that family writes these sounds
| /ʃ/ in a modern French loan | chmachine, chef |
What gives it away on the page
| -eau, -oir/-oire, ch said as /ʃ/, silent final consonant | Modern French — borrowed after French itself stopped pronouncing final consonants.bureau, memoir, machine, chef, ballet, debut, gourmet |
Placing it without the spelling
| /ʃ/ where an older loan would have said /tʃ/ | Modern French, borrowed after the sound shiftedmachine, chef |
Later and wider borrowings in the spelling guide · guess another word's family