N-type oxide gas sensor,N型氧化物气敏元件

nuclear electric quadrupole moment resonance spectroscopy,核四极共振波譜法

Nuclear Instrument Module (NIM),核儀器模塊

nuclear magnetic double resonance,核磁雙共振（法）

nuclear magnetic resonance magnetometer,核磁共振磁強計

nuclear magnetic resonance spectroscopy;NMR spectroscopy,核磁共振波譜法

nuclear radiation thickness meter,核輻射厚度計

(nuclear)radiation transducer [sensor],（核）輻射式傳感器

nuclei counter,計核器

nude source,裸式离子源

null measurement,指零測量

null method,零位法

null method of measurement,零位測量法；指零測量法；零差測量法

null reading method,零讀法

number of degrees of freedom,自由度數

number of effective plate,有效板數

number of theoretical plate,理論板數

numeric key,數字鍵

numerical aperture (NA),數值孔徑

numerical control,數值控制

numerical value (of a quantity),（量的）數值

nutating disc flowmeter,（章動）圓盤流量計

nutating flowmeter,章動流量計

nutrients,營養鹽

nutrients analyzer for seawater,海水營養鹽分析器

Nyquist plot,奈奎斯特圖

object language,目標語言

object plane,物面

object program,目標程序

object wave,物体聲束

objective evidence,客觀証据

objective lens of the scanning electron microscope,掃描電子顯微鏡物鏡

objective lens of the transmission electron microscope,透射電子顯微鏡物鏡

oblique visibility,斜能見度

observability,可觀測性；能觀測性

observation and recording device,觀察和記錄裝置

ocean bottom seismograph,海底地震儀

ocean date station,浮標站

oceanographic geological instrument,海洋地質儀器

oceanographic instrumentation,海洋儀器

oceanographic measuring system,海洋測量系統

oceanographic observation,海洋觀測

oceanographic survey,海洋調查

octave,倍頻程

octave(bandwidth)filter,倍頻程（寬帶）濾波器

octave filter set,倍頻程濾波器組

odd-even check,奇偶校驗

off-axis response,离軸響應

off-line,离線

off-line processing,离線處理；脫机處理

off-line system simulation,离線系統仿真

office automation (OA),辦公自動化

office automation system (OAS),辦公自動化系統

office information system (OIS),辦公信息系統

officially recognized standard,官方認可標准

offset,靜差

offset coefficient,靜差系數

oil-filled enclosure (Ex o),充油外殼（Ex o）

oil-water meter,原油水分儀

omegatron mass spectrometer,回旋質譜計

omnidirectional microphone,全向傳聲器

on-cold column injector,冷柱頭進樣器

one-dimensional location,線定位；一維空間定位

on-line,在線

on-line assistence,在線幫助

on-line measurement and frequency spectrum analysis,在線測量頻譜分析

on-line process gas chromatograph,在線過程气相色譜儀

on-line processing,在線處理；聯机處理

on-line real-time processing,在線實時處理

on-line real-time system,聯机實時系統

on-line system simulation,在線系統仿真

on-off action,通斷作用

on-off controller,通斷控制器

one-man atmospheric submersible,常人常壓潛水器

one-third octave filter,1/3倍頻程濾波器

one-turm time of output shaft,輸出軸每轉時間

one-way communication,單向通信

open-circuit intermediate voltage,開路中間電壓

open front case with pressure relief,帶泄壓裝置的前開式外殼

open front case without pressure relief,無泄壓裝置的前開式外殼

(open hole) caliper,井徑儀

open-jet wind tunnel,開口式風洞

open loop,開環

open loop control,開環控制

open loop control system,開環控制系統

open loop electronic balance,開環式電子天平

open-loop frequency response,開環頻率響應

open-loop gain,開環增益

open-loop gain characteristic,開環增益特性

open loop pole,開環极點

open loop process control,開環過程控制

open loop remote control system,開環遙測控制系統

open loop stabilization,開環穩定

open loop transfer function,開環傳遞函數

open loop voltage gain,開環電壓增益

open loop zero,開環零點

open source,裸式离子源

open system,開放系統；開環系統