word | | Terrain |
| uninhabited | Saudi Arabia | mostly uninhabited, sandy desert |
| unique | Indian Ocean | surface dominated by counterclockwise gyre (broad, circular system of currents) in the southern Indian Ocean; unique reversal of surface currents in the northern Indian Ocean; low atmospheric pressure over southwest Asia from ... |
| unusually | Southern Ocean | ... extent with only limited areas of shallow water; the Antarctic continental shelf is generally narrow and unusually deep, its edge lying at depths of 400 to 800 m (the global mean is ... |
| Upland | Azerbaijan | ... Lowland) (much of it below sea level) with Great Caucasus Mountains to the north, Qarabag Yaylasi (Karabakh Upland) in west; Baku lies on Abseron Yasaqligi (Apsheron Peninsula) that juts into Caspian Sea |
| upland | India | upland plain (Deccan Plateau) in south, flat to rolling plain along the Ganges, deserts in west, Himalayas in north |
| upland | Panama | interior mostly steep, rugged mountains and dissected, upland plains; coastal areas largely plains and rolling hills |
| upland | Sierra Leone | coastal belt of mangrove swamps, wooded hill country, upland plateau, mountains in east |
| upland | West Bank | mostly rugged dissected upland, some vegetation in west, but barren in east |
| upland | Yemen | narrow coastal plain backed by flat-topped hills and rugged mountains; dissected upland desert plains in center slope into the desert interior of the Arabian Peninsula |
| uplands | Germany | lowlands in north, uplands in center, Bavarian Alps in south |
| uplands | Luxembourg | mostly gently rolling uplands with broad, shallow valleys; uplands to slightly mountainous in the north; steep slope down to Moselle flood plain in the southeast |
| uplands | Mozambique | mostly coastal lowlands, uplands in center, high plateaus in northwest, mountains in west |
| uplands | Russia | broad plain with low hills west of Urals; vast coniferous forest and tundra in Siberia; uplands and mountains along southern border regions |
| uplands | Rwanda | mostly grassy uplands and hills; relief is mountainous with altitude declining from west to east |
| uplifted | Tonga | most islands have limestone base formed from uplifted coral formation; others have limestone overlying volcanic base |
| Upolu | Samoa | two main islands (Savaii, Upolu) and several smaller islands and uninhabited islets; narrow coastal plain with volcanic, rocky, rugged mountains in interior |
| Urals | Russia | broad plain with low hills west of Urals; vast coniferous forest and tundra in Siberia; uplands and mountains along southern border regions |
| urban | Holy See (Vatican City) | urban; low hill |
| usually | Atlantic Ocean | surface usually covered with sea ice in Labrador Sea, Denmark Strait, and coastal portions of the Baltic Sea from October to June; clockwise warm-water gyre (broad, circular system of currents) in ... |
| usually | Palau | varying geologically from the high, mountainous main island of Babelthuap to low, coral islands usually fringed by large barrier reefs |
| Vakhsh | Tajikistan | Pamir and Alay Mountains dominate landscape; western Fergana Valley in north, Kofarnihon and Vakhsh Valleys in southwest |
| valley | Armenia | Armenian Highland with mountains; little forest land; fast flowing rivers; good soil in Aras River valley |
| valley | Chile | low coastal mountains; fertile central valley; rugged Andes in east |
| valley | Egypt | vast desert plateau interrupted by Nile valley and delta |
| Valley | Ethiopia | high plateau with central mountain range divided by Great Rift Valley |
| valley | Georgia | ... the south; Kolkhet'is Dablobi (Kolkhida Lowland) opens to the Black Sea in the west; Mtkvari River Basin in the east; good soils in river valley flood plains, foothills of Kolkhida Lowland |