What does U/ stand for?

At the Umbilicus [Obstetrics] (DAVI)

Asymmetrical [Chemistry] (BARN)

Audio and Power Connectors [JETDS nomenclature] [Military] (CET)

Benzon [Denmark] [Research code symbol]

Eased Up [Horse racing]

Eaton Laboratories, Inc. [Research code symbol]

Electric Tension [Symbol] [IUPAC]

General, Utility [Communications term] (DCT)

Heat Transfer Coefficient (BARN)

Internal Energy [Symbol] [Thermodynamics]

International Unit [of enzyme activity] (DAVI)

Intrinsic Energy [Symbol] [Physics]

Key Undetermined [Music]

Mann-Whitney Rank Sum Statistic (STED)

Potential Difference [in Volts] (DMAA)

Quartermon Versor [Symbol of a function] [Mathematics] (ROG)

Shape Descriptor [U-turn, for example. The shape resembles the letter for which it is named]

Thermal Transmittance per Unit of Area [Heat transmission symbol]

Uafhaengige Parti [Independent Party] [Denmark] [Political party] (PPE)

Ubiquinone [Coenzyme Q] [Also, CoQ, Q, UQ] [Biochemistry]

U-boat (SAUS)

Ugly Sky [Navigation]

Ugly Threatening Weather [Meteorology]

Ugutio [Huguccio] [Deceased, 1210] [Authority cited in pre-1607 legal work] (DSA)

Uhr [Clock] [German]

Ullage (AAG)

Ulna (STED)

Ultra High Frequency [Also, UHF] (DOAD)

Ultralente Insulin [Pharmacology] (DAVI)

Ultraphon & Supraphon [Record label] [Former Czechoslovakia]

Umpire [Baseball]

Unassisted Putout [Baseball term] (NDBD)

Unbalanced

Unburned [Ecology]

Uncertain (STED)

Uncirculated

Unclassified

Uncle [Phonetic alphabet] [Royal Navy] [World War I] [Pre-World War II] [World War II] (DSUE)

Uncommon Species

Und [And] [German]

Undefined (IAA)

Under

Underfloor (NASA)

Underwater [Missile launch environment symbol]

Unemployed Parent [Aid to Families with Dependent Children] (OICC)

Unemployment

Unerupted (MAE)

Unicom (PIPO)

Unified

Unified Atomic Mass [Physics] (WDAA)

Unified Atomic Mass Unit [Nuclear energy] (IAA)

Uniform [Phonetic alphabet] [International] (DSUE)

Uniformly Labeled [Also, UL] [Compound, with radioisotope]

Union [or Unionist]

Union Association [Major league in baseball, 1884]

Unionist (WDAA)

Unionist Party [Northern Ireland] [Political party]

Union of Sets (IDOE)

Unit

Unitarian [Medicine] (EDAA)

United

United Shareowners of America (EA)

United States Air Group [NYSE symbol] (SAG)

United States Fastener Manufacturing Group (EA)

United States Salvage Association (EA)

Unit of Measure (IAA)

Unity Matrix (ACAE)

Universal

Universal Set (IDOE)

Universal/Unrestricted [Film certificate] [British]

Universe (MHDB)

University

Unix Systems Association (EA)

Unknown

Unknown Intensity [Weather codes - aviation] (PIPO)

Unlicensed (DA)

Unlimited Time [Broadcasting term]

Unnumbered

Unnumbered Acknowledge [or Acknowledgement] [Telecommunications] (IAA)

Unoccupied

Unpleasant

Unprotected [Communications term] (DCT)

Unsatisfactory (GOBB)

Unseated Rider [Horse racing]

Unsubscribe [Computer science] [Telecommunications]

Unsymmetrical

Unter [Among] [German]

Until (DA)

Untreated [Medicine]

Unverified [Aviation] (PIPO)

Unwatched [With reference to a light] [Maps and charts]

Up [or Upper]

Update [Computer science]

Upjohn Co. [Research code symbol]

Upper (ROG)

Upper Bow [Music] (ROG)

Upper-Class Speech ["Non-U" designates the opposite]

Upper School [British]

Upstage (WDMC)

Uracil [Biochemistry] (MAE)

Uranium [Chemical element]

Urban [District Council] [British]

Urban Association [Baseball]

Urethra (STED)

Urgent

Uridine [One-letter symbol; see Urd]

Uridylic Acid [Biochemistry] (DB)

Urinal (ROG)

Urinary Concentration [Medicine] (STED)

Urinate [or Urine] [Medicine]

Urine (DAVI)

Urological Surgery [Medical specialty] (DHSM)

Urologist (DAVI)

Urology (DAVI)

Urschrift [Original, as of a document] [German military]

Uruguay [IYRU nationality code]

USAIR Group [NYSE symbol] (SPSG)

Use

Utah

Utah Reports [A publication] (DLA)

Utah State Library, Salt Lake City, UT [Library symbol] [Library of Congress] (LCLS)

Utendus [To Be Used] [Pharmacy]

Utility [Designation for all US military aircraft]

Utterance [Linguistics] (IEL)

UTVA Aircraft Factory [Former Yugoslavia] [ICAO aircraft manufacturer identifier] (ICAO)

Uvula (STED)

U-Wave [on electrocardiogram] [Cardiology] (DAVI)

You [Telegraphy] (PCTE)

You [Amateur radio shorthand] (WDAA)

Australasia [MARC geographic area code] [Library of Congress] (LCCP)

Density of Radiant Energy (SAUS)

Group Velocity [Symbol] (DEN)

Micro (IDOE)

Micron (DAVI)

Uebersetzen [Translate] [German]

Undelete [Computer science] [Telecommunications]

Underfloor (NAKS)

Unified Atomic Mass Unit (IDOE)

Unit (MIST)

Unpaved Surface [Aviation] (DA)

Up (quark) [Atomic physics]

Velocity [Symbol]