U Gem Stars
U-invariant closed subspace
UA1
UA2
Uaru
Uberabatitan
Uchucchacuaite
Udoteaceae
Ueda attractor
Uelia
Uenasellus
Uhlenbeck, George Eugene
* Uhlenbeck, Karen
Uhuru SAS-1/Explorer 42 satellite
Uintacrinus socialis
Ukichiro Nakaya
Uklonskovite
Ulakanthura
Ulleria
Ullmannite
Ulm factor
Ulmaceae
Ulmaridae
Uloboroidea
Uloma culinaris
Ulotrichales
Ulrichite
Ultracold neutrons
Ultra fast laser spectroscopy
Ultrashort pulse
Ultrasound attenuation spectroscopy
Ultraviolet (UV)
Ultraviolet Astronomy
Ultraviolet divergence
Ultraviolet fixed point
Ultraviolet photoelectron spectroscopy (UPS)
Ulvaceae
Ulvales
Ulvellaceae
Ulvipinara
Ulvophyceae
Ulyanidae
Umangite
* Umawi, Abu al
Umbellulidae
Umbilic torus
Umbite
Umbonulomorpha
Umbriel
Umbrina
Umbrivaga
Unassigned Asterids
Unassigned Caryophyllales
Unassigned Diprotodontia
Unassigned Eudicots
Unassigned (Gammaridea)
Unassigned Rosids
Unbibium
Unbinilium
Unbiquadium
Unbitrium
Unbiunium
Uncarina grandidieri,
Uncia
Uncia uncia
Uncicida
Unclassified Elateriformia
Ungaliophis
Uniform Distribution
Uniola
Unionidae
Unionoidea
Unique Factorization Theorem
Unit circle
Unit square
United Kingdom Infrared Telescope (UKIRT)
Universal Turing machine
Universal quantum simulator
Universe
University of Crete Observatory
University of Cyprus
University Ludwig Maximilians Observatory
Unplaced Malphighialids
Unsöld, Albrecht
Ununennium
Ununhexium
Ununoctium
Ununpentium
Ununquadium
Ununseptium
Ununtrium
Up quark
Upalite
Upis ceramboides
Upogebiidae
Uppsala Astronomical Observatory (UAO)
UPS (Ultraviolet photoelectron spectroscopy)
Upselaspis
* Uqlidisi, Abu'l al
* Upton, Francis
Upupa
Upupa epops
Upupidae
Uracanthini
Uracil
Uraeginthus
Uraeginthus bengalus
Uraeginthus granatina
Uragus
Uragus sibiricus
Uraniidae
Uraniinae
Uraninite
Uranium
Uranophane
Uranopilite
Uranoscopidae
Uranus
Urca-process
Urceolina
Urceolina urceolata,
Urea
Uredinales
Urediniomycetes
Urey, Harold Clayton
Uria
Uria aalge
Uridine
Uricite
Urnaloricidae
Urochondra
Urochroa
Urocissa
Urocissa erythrorhyncha
Urocynchramus
Urodontinae
Urolais
Urolophidae
Uromacer
Uromacerina
Uromastyx
Uromastyx aegyptia
Uromastyx ornata ornata
Uromys
Uropelia
Uropeltidae
Uropeltis
Uropterygiinae
Uropygi
Urorhipis
Urosphena
Urosticte
Urosticte benjamini
Urosticte ruficrissa
Urota
Urota centralis
Urota melichari
Urotheca
Urothemistinae
Urothraupis
Urotini
Urotriorchis
Ursa Major
Ursa Major Moving Group
Ursa Minor
Ursus
Ursus americanus
Ursus arctos
Ursus arctos beringianus
Ursus deningeri
Ursus maritimus
Ursus pelaeus
Ursus thibetanus
Urtea
Urticaceae
Uruminopeplus
* Urysohn, Pavel
US Naval Observatory
Ussher, James
Ustilaginomycetes
Ustilaginomycetidae
Uta stansburiana
Uvarovite
