navis

Latin navis meant 'ship' and came from Proto-Indo-European *neh₂u-s, one of the oldest reconstructed words in the language family. Sanskrit had nau, Greek had naus (ναῦς), Old Irish had nau. The word for ship was so ancient and so stable that it barely changed across thousands of years and thousands of miles. People needed boats. The word for boat persisted.

Old French reshaped navis into navie, meaning 'a fleet of ships,' and English borrowed it as navy by the early 14th century. The meaning narrowed from any fleet to specifically a nation's warships. Meanwhile, navis branched in unexpected directions. The nave of a church — the long central hall where the congregation sits — was named for its resemblance to an inverted ship hull. Walk into any Gothic cathedral and look up: the vaulted ceiling is a boat turned upside down.

Greek naus gave English nausea — literally 'ship-sickness,' the queasiness of being at sea. Nausea traveled from Greek through Latin and into English unchanged. It also produced nautical, astronaut ('star sailor'), and navigate (from Latin navigare, 'to drive a ship'). Every word about steering, sailing, or feeling seasick traces back to the same Indo-European boat.

The Royal Navy, founded by Henry VII in 1509, became the instrument of the British Empire. By 1805 — the year of Trafalgar — it was the most powerful military force on earth. A word that had meant 'ship' for five thousand years now meant global hegemony. Nelson died on his flagship, and the navy he commanded was, etymologically, just a collection of boats.