Suffix · forms nouns
From Greek "metron" (to measure): names measuring instruments or metric units. Thermometer, kilometer.
Written by Bryan López, English teacher · Updated
The suffix -meter comes from Greek "metron" (measure) and names measuring instruments or metric units. From "thermo-" (heat) comes "thermometer"; from "baro-" (atmospheric pressure) comes "barometer". The Spanish equivalent is -metro or -ímetro: thermometer → termómetro, barometer → barómetro. Spanish sometimes adds a linking vowel that English does not.
The first part identifies what is measured: thermo- (heat): thermometer baro- (pressure): barometer speed-: speedometer kilo- (×1000): kilometer centi- (÷100): centimeter milli- (÷1000): millimeter alti- (altitude): altimeter volt-: voltmeter hygro- (humidity): hygrometer gas: gas meter
"Meter" has two functions in English: 1. Unit of length (= metro): "The room is 5 meters wide." 2. Suffix meaning measuring instrument: thermometer, speedometer. In American English: "meter" for both. In British English: "metre" for the unit of length and "meter" for the instrument. International scientific texts use "metre" for the unit. The word family: -meter (instrument), -metry (science of measuring), -metric (adjective). Example: geometry (geo = earth + metry).
Greek/Latin root (what is measured) + meter.
Word family: -meter (instrument or unit), -metry (science of measuring), -metric (adjective). Geometry (geo = earth + metry). Symmetric, parametric, metric.
-meter/miːtər/ · stress falls on the syllable before it
Tap the button to hear how the ending sounds. Each word in the table has its own audio.
"The room is 5 meters wide" = unit of length. "The thermometer reads 37°" = measuring instrument. Same word, two uses.
In American English always -meter. In British English, -metre only for the unit of length; instruments are always spelled -meter.
"speedometer" (not "speedmeter"). speed + ometer — the linking vowel -o- joins root and suffix in many Greek compounds.
A trick to remember it
-meter = instrument that measures. First identify what it measures: thermo- (heat), baro- (pressure), speed- (velocity). Also appears in SI units: kilo-meter, centi-meter, milli-meter. Word family: -metry (science), -metric (adjective).
Exercise 1 · Form the word
Exercise 2 · Pick the right one
A "barometer" is used to measure...
Exercise 3 · Pick the right one
"Kilometer" and "centimeter" are...
The suffix -meter from Greek "metron" (to measure): names measuring instruments or metric units. Thermometer, kilometer. In Spanish it usually maps to -metro / -ímetro.
The ending -meter is pronounced /miːtər/ · stress falls on the syllable before it. For example, "thermometer".
"thermo (heat)" becomes "thermometer". It is a typical example of the -meter suffix.
-tion, -ness, -ful, -ly, -able... every ending you need to understand thousands of words at once.