uncertainty,不确定度

uncertainty of measurement,測量不确定度

uncorrected result,未修正結果

uncoupled modes,非耦合振型

undampted natural frequency,無阻尼固有頻率

undamped natural mode of vibration,無阻尼固有振動模態

under water acoustic measurment,水聲綜合測量儀

underdamping,周期阻尼；欠阻尼

undersea buoy system,水下浮標系統

understandability,可理解性

underwater absorption meter,水下吸收儀

underwater acoustic,水（下）聲學

underwater acoustic communication set,水下通訊裝置

underwater acoustic measurement,水聲測量

underwater acoustic transducer,水聲換能器

underwater camera,水下照相机

underwater communication system,水下通訊裝置

underwater holography,水下全息攝影

underwater irradiance meter,水下輻照度計

underwater lighting system,水下照明裝置

underwater movie camera,水下電影攝影机

underwater panoramic camera,水下全景照相机

underwater polarimeter,水下偏振儀

underwater radiance meter,水下輻射率計

underwater scattering meter,水下散射儀

underwater sound,水（下）聲學

underwater sound integrated measuring set,水聲綜合測量儀器

underwater sound test tank,水聲試驗水池

underwater television camera,水下電視攝像机

underwater towed system,水下拖曳系統

underwater towed vehicle,水下拖曳体

underwater transducer array,水聲換能器基陣

underwater transmissometer,水下透射率儀

underwater vehicle,水下運載工具

underwater visibility,水下能見度

underwater window,水下﹛窗口﹛

undetermined components,非測組分

unearthed voltage transformer,不接地型電壓互感器

uniaxial strain gauge,單軸應變計

uniform stability,一致穩定性

uniform temperature zone,均溫區

uniform temperature zone length,均熱帶長度

uniformity of table motion,台面運動的均勻度

union nut,雙端螺母

unit,單元；單位

unit(of measurement),（測量）單位

unit area acoustic impedance,聲阻抗率

unit feedback,單位反饋

unit resolution,單位分辨

unit resolution mass,單位分辨質量

unit step function,單位階躍函數

universal balancing machine,通用平衡机

universal gas chromatograph,通用气相色譜儀

universal head loss coefficient,通用壓頭損失系數

universal testing machine,万能試驗机

universal toolmaker's microscope,万能工具顯微鏡

unmanned submersible,無人潛水器

unsaturated standard cell,不飽和式標准電池

unsteady flow,不穩定流

upper-air observation,高空觀測

upper limit of the nominal of use for frequency,標稱使用頻率范圍上限

upward (total) radiation,向上（全）輻射

upward terrestrial radiation,向上地球輻射

urea enzyme transducer [sensor],　（式）尿毒傳感器

urinary bladder inner pressure transducer [sensor],膀胱內壓傳感器

usable cross-section of the test channel,試驗流道的可用橫截面

usable minimum immersion depth,最小可用浸入深度

useful life,使用壽命

useful spectral range,有效光譜范圍

user adjustment,用戶調整

user layer,用戶層

utility routine,服務程序；實用程序；實用例行程序

utility software,實用軟件

UV dosimeter,紫外線表

UVW anemometer,三維風速表；UVW風速表

vacancy chromatography,空穴色譜法

vacuum,真空；負壓

vacuum accumulator,真空貯气筒

vacuum correction,真空修正

vacuum drying chamber,真空干燥箱

vacuum evaporator,真空鍍膜台

vacuum fusion gas chromatography,真空熔融气相色譜法

vacuum gauge,真空表；真空規管

vacuum system,真空系統

vacuum transducer [sensor],真空[負壓]傳感器

vacuum valve,真空閥門

validity check,有效性檢驗

validity event,有效事件

valley,谷

Vallot helio-thermometer,瓦勞特日光溫度表

value analysis,价值分析

value engineering,价值工程

value (of a quantity),（量）值

value of image shift,圖象漂移量

value of scale division,標度分格值

value of scale mark,標度值

values transfer,量值傳遞

valve,閥