neh₂-w-tó-
“skilled in water, seafarer”nautical, navy, navigate, nausea
Participial of *neh₂-w- giving Greek nautes, English nautical, navy, navigate, nausea.
Discussion
The PIE form *neh₂-w-tó- (skilled in water, seafarer) is a compound adjective built from *neh₂-u- (boat, ship — itself from the verbal root *neh₂- "to swim, to float") with the agentive/adjectival suffix *-tó-. The literal sense is "one who belongs to boats" or "water-skilled" — a seafarer, a navigator.
The Greek reflex naútēs (ναύτης, "sailor") is the most transparent continuation, preserving both elements with minimal change. From naútēs and its base naûs (ναῦς, "ship") Greek generated a rich maritime vocabulary: nautikós (nautical), nausía (nausea — literally sea-sickness, the sickness of ships), Argonautai (the Argonauts, "sailors of the Argo"), and the combining form nau- that persists in English: navy, naval, navigate (from Latin nāvigāre, literally "to drive a ship"), and astronaut (star-sailor, coined 1920s on the Greek model).
Latin nāvis (ship) continues the base noun *neh₂-u- and generated its own derivative chain: nāvālis (naval), nāvigāre (to navigate), nāvigium (vessel), and the ecclesiastical nave (the central body of a church, so called because its vaulted ceiling resembles an inverted ship's hull). The metaphor of the church as a ship — navis ecclesiae — is one of the oldest in Christian architectural vocabulary.
Sanskrit nau- (boat, ship) and the related nāvya- (navigable) preserve the Indo-Iranian reflex. The Vedic compound nau-pati- ("ship-master") is a direct structural parallel to Greek naúklēros (ship-owner), both compounds of the PIE boat-word with a word for master or lord.
Old Irish nau (ship) and Welsh noe (a trough, possibly related) provide Celtic attestation, though the Celtic forms are less productive than the Graeco-Latin and Indo-Iranian reflexes.
The reconstruction of *neh₂- as a PIE root implies that the speakers of Proto-Indo-European were familiar with watercraft — a detail that has been used in arguments about the PIE homeland, which most scholars now place in the Pontic-Caspian steppe region north of the Black and Caspian seas, where river navigation would have been essential. The word's survival across all major branches, from Hittite (not securely attested for this root) through Greek, Latin, Sanskrit, and Celtic, confirms it as core PIE vocabulary rather than a regional innovation.
The nausea connection deserves special note. Greek nausía (literally ship-sickness) passed through Latin nausea into English, where it now means any kind of sickness or disgust — the maritime origin entirely forgotten. The phrase "I feel nauseous" is, etymologically, "I feel as though I am on a ship."