- U
- U2
- U-235
- U-238
- U-239
- U4E
- ua
- U.A.E.
- uakari
- UAM
- ua mau ke ea o ka aina i ka pono
- u. & l.c.
- UAP
- U.A.R.
- UART
- UAS
- Uaupés
- UAV
- UAW
- U.B.
- UB40
- Ubangi
- Ubangi-Shari
- Ube
- U-bend
- uber
- Uberaba
- Uberlândia
- Übermensch
- uberrima fides
- ubersexual
- UBI
- ubiety
- ubique
- ubiquinone
- Ubiquitarian
- ubiquitin
- ubiquitous
- ubiquity
- ubi sunt
- ubi supra
- U-boat
- U-boats
- U bolt
- UBR
- Ubuntu
- UBV photometry
- u.c.
- UCAS
- UCATT
- Ucayali
- UCC
- UCCA
- Uccello
- Uccle
- UCE
- UCL
- UCMJ
- UCR
- UCT
- U.C.V.
- U/D
- UDA
- UDAG
- Udaipur
- udal
- Udall
- U.D.C.
- udder
- UDI
- Udine
- Udmurt
- Udmurt Autonomous Republic
- Udmurt Republic
- udo
- udometer
- udon
- Udon Thani
- UDR
- UEFA
- Uele
- uey
- Ufa
- U.F.C.
- Uffizi
- Uffizi Gallery
- UFO
- ufology
- UFT
- UFW
- ug
- ugali
- Uganda
- Ugandan
- Ugarit
- Ugaritic
- UGC
- ugh
- Ugli
- uglify
- ugly
- Ugly American
- ugly as sin
- ugly customer
- ugly duckling
- Ugrian
- Ugric
- ugsome
- uh
- Uhde
- UHF
- uh-huh
- uhlan
- Uhland
- uh-oh
- Uhry
- UHT
- uh-uh
- uhuru
- UI
- Uigur
- uilleann pipes
- uillean pipes
- uintaite
- Uinta Mountains
- uintathere
- Uisliu
- Uisnech
- UIT
- uitlander
- uitwaaien
- ujamaa village
- Ujiji
- Ujjain
- Ujpest
- Ujung Pandang
- U.K.
- UKAEA
- ukase
- UKBA
- UKCC
- uke
- Ukiah
- UKIP
- ukiyo-e
- UK Overseas Territory
- Ukr.
- Ukraine
- Ukrainian
- ukulele
- UL
- ʿulama
- ulan
- Ulan Bator
- Ulanova
- Ulan Ude
- Ulbricht
- ULCC
- ulcer
- ulcerate
- ulceration
- ulcerative
- ulcerative colitis
- ulcerogenic
- ulcerous
- ule
- Uleåborg
- ulema
- ulexite
- ULF
- Ulfilas
- Ulhasnagar
- uliginous
- ullage
- ullage rocket
- Ullswater
- ulluco
- Ulm
- ulmaceous
- ulna
- ulnar nerve
- ulno-
- ulotrichous
- -ulous
- ulpan
- Ulpian
- Ulsan
- Ulster
- Ulster Defence Association
- Ulster Democratic Unionist Party
- Ulsterman
- Ulster Unionist Council
- ult.
- ulterior
- ultima
- ultimacy
- ultima ratio regum
- ultimate
- ultimate constituent
- ultimately
- ultimate strength
- ultima Thule
- ultimatum
- ultimo
- ultimogeniture
- ultisol
- ulto.
- ultra
- ultrabasic
- ultracentrifuge
- ultraclean
- ultraconservative
- ultracrepidarian
- ultracritical
- ultradian
- ultra-distance
- ultrafast
- ultrafiche
- ultrafilter
- ultrafiltrate
- ultra filtration
- ultrahigh
- ultrahigh frequency
- ultraism
- ultralarge crude carrier
- ultraleft
- ultraleftist
- ultraliberal
- ultralight
- ultralow frequency
- ultramafic
- ultramarathon
- ultramarine
- ultrametamorphism
- ultramicrobalance
- ultramicrochemistry
- ultramicrofiche
- ultramicrometer
- ultramicroscope
- ultramicroscopic
- ultramicroscopy
- ultramicrotome
- ultraminiature
- ultraminiaturize
- ultramodern
- ultramontane
- ultramontanism
- ultramundane
- ultranationalism
- ultranationalist
- ultranet
- ultrapure
- ultrared
- ultraright
- ultrarightist
- ultrashort
- ultrasonic
- ultrasonic cleaning
- ultrasonics
- ultrasonic testing
- ultrasonic welding
- ultrasonography
- ultrasound
- ultrasound scanner
- ultrastructure
- Ultrasuede
- ultrathin
- ultratropical
- ultraviolet
- ultraviolet astronomy
- ultraviolet filter
- ultraviolet radiation
- ultra vires
- ultravirus
- ultrawideband
- ulu
- Ulúa
- ululant
- ululate
- ululation
- Ulundi
- Uluru
- Ulyanovsk
- Ulysses
- um
- umami
- Umar
- Umar Tal
- Umayyad
- umbel
- umbellate
- umbellet
- umbelliferous
- umbellule
- umber
- umber moth
- Umberto
- Umberto I
- Umberto II
- umbilical