U Value (Coefficient of Heat Transmission)

U&O (Utility and Offsite)

U.S. Customary Unit

U.S. Dollar Index (USDX)

U/G Duct Bank Layout Drawing

Ubiquitous

Ubiquitous Computing

UCC (Universal Copyright Convention)

UDD (Utility Distribution Diagram)

UEF (United Engineering Foundation Inc.)

UHD (Utility Head Diagram) or Utility Flow Diagram (UFD)

UIU (Up index Up)

UK Continental Shelf (UKCS)

ULC (Unit Labour Cost)

ULCC (Ultra Large Crude Carrier)

Ulexite

Ullage

Ultimate

Ultimate Analysis

Ultimate Beneficial Owner (UBO)

Ultimate Control Enterprise

Ultimate Strength

Ultimate Tensile Strength

Ultra Heavy Oil

Ultra Large Crude Carrier (ULCC)

Ultra Low Sulphur Fuel Oil (ULSFO)

Ultrafiltration (UF) Membrane

UN (United Nations)

UN ESCAP (United Nations Economic and Social Commission for Asia and the Pacific)

UN ID; UN Number; UN Number Code; UN/NA Number

UN PRI (UN Principles for Responsible Investment)

Unavailability

Unbundling

Uncertainty

Unclassified Public Information

Unconditional Bond

Unconformity

Unconventional

Unconventional Oil

Unconventional Reservoirs

Undependability

Under Coverage

Under Estimate

Under Ground

Underground Composite Drawing

Underfunding

Undergo

Underground Blowout

Underground Economy

Underground Feeder (UF)

Underground Production

Underground Services Detail Drawing

Underground Services Layout

Underground Services Specification

Underground Storage

Underlying

Understand

Underwriter

Undisbursed

UNEP (United Nations Environment Programme)

UNESCO (United Nations Educational, Scientific and Cultural Organization)

UNFCC (United Nations Framework Convention on Climate Change)

Unfinished Oil

Unfold

Unforeseen

Unforeseen Obsolescence

Unfractionated Streams

UNIDO (United Nations Industrial Development Organization)

Uniform Corrosion

Unimodal Distribution

Unincorporated Business

Unincorporated Enterprise

Unique

Unique Item

Unit

Unistatus

Uniqueness

Unique Product

Unit Cost

Unit Of Measure

Unit Operation

Unit Price Contract

Unitary

United Nations System Influenza Coordination (UNSIC)

Unitisation (Unitization)

Universal Gas Constant 

Universal Service

Universal Solvent

Unknown

Unpaid Labour

Unproven Reservoir

Unquoted Public Company

Unrelated Diversification

Unreliability

Unrestricted Area (Non-Controlled Area)

Unrevealed Failure

Unsaturated Fat

Unsaturated Hydrocarbon

Unsaturated Solution 

Unstable

Unstable Material

Unsteady State

Untact

Untied Aid

Ununpentium (Uup)

Unvented Heater

Upcycle

Upgrade

Uphold

Upper Bound

UPS (Uninterruptible Power Supply)

UPS (Uninterruptible Power Supply) One Line Diagram

Upset

Upstream (Institute)

Upstream Business

Upstream Engineering

Upstream, Midstream and Downstream

Uptime

Uranium (U)

Uranium Oxide

Uranium Conversion

Uranus

Urban

Urban Air Mobility (UAM)

Urban Runoff

Urban Sprawl

Urbanisation

Urea (CO(NH2)2)

Urea Resin 

Urethane

Uric Acid (C5H4N4O3)

URL (Uniform Resource Locator or Universal Resource Locator)

URS (User Requirement Specification)

Used Asset

User

User Acceptance Test (UAT)

User Interface

User Satisfaction Survey

USGS (United States Geological Survey)

USPS (U.S. Postal Service)

USR (User System Requirement)

USTR (U.S. Trade Representative)

UT (Ultrasonic Testing)

Utilisation (Utilization)

Utilise (Utilize)

Utility

Utility Facility

Utility Interactive Inverter

UV Index (UVI)

UV Radiation (Ultraviolet Radiation)