ud-
“up, out, upward”up/upward
PIE preposition meaning up, out, or upward. Source of English "out," Latin ūs-, and words for upward motion.
Discussion
*ud- is a Proto-Indo-European preposition meaning "up," "out," or "upward," expressing vertical motion away from a surface or interior.
The root gives Old English ūt "out" (modern English out, utter, utmost, outward) and up (from an extended form *ud-po- or related to *upo). German aus "out" and Dutch uit continue the Germanic pattern. Old Norse út gives Scandinavian ut/ud forms.
Latin ūs- (in ūsque "all the way") may contain this root, though the connection is debated. Greek hýsteros "later, latter" (whence English hysteria, originally "womb-suffering," from hystéra "womb"—the connection to *ud- being spatial) is sometimes linked to this root.
Sanskrit ud- "up, out" is the most transparent reflex, preserved as a productive prefix in Sanskrit compound verbs (utthāna "rising up," udaya "rising, dawn"). Lithuanian už- "behind" shows a Balto-Slavic extension.
The root belongs to the PIE vertical axis system alongside *n̥dʰer- "under" and *upo "up from below/over." The distinction between *ud- (outward/upward motion) and *upo (position above/below) reflects PIE precision in spatial description.
Modern descendants include English out, outer, utter, utmost, and the Sanskrit-derived prefix ud- in yoga terminology.
Notes
Source of Latin "ūsque", English "out", Sanskrit "úd". Upward/outward vector.