Suffix · forms nouns
Turns adjectives into nouns naming a dimension or abstract quality: wide becomes width.
Written by Bryan López, English teacher · Updated
The suffix -th turns adjectives (and some verbs) into nouns naming a measurement, dimension or abstract quality. From "wide" comes "width"; from "long" comes "length"; from "strong" comes "strength". It is an old Germanic English suffix that is not productive today: you cannot add it to new adjectives. There is a fixed set of -th words to memorise.
This group of -th words is essential vocabulary for talking about dimensions and qualities: width = anchura (from "wide") length = longitud (from "long") height = altura (from "high") depth = profundidad (from "deep") strength = fuerza (from "strong") health = salud (from "hale", archaic) growth = crecimiento (from "grow") truth = verdad (from "true") wealth = riqueza (from "wealthy") warmth = calidez (from "warm")
The suffix -th is pronounced /θ/, the voiceless "th" sound as in "thin" or "think": place the tip of your tongue lightly between your teeth and push air through. Do not confuse it with: - /ð/ (voiced "th"): "the", "this", "that" — here the tongue vibrates. - /t/: -th in English never sounds like plain /t/. Examples: width = /wɪdθ/, length = /leŋkθ/, strength = /streŋkθ/. The final consonant cluster can be tricky: practise aloud.
Adjective + th. Closed class — not productive with new words.
Some words have phonetic changes when adding -th: long → length (a k/g sound appears), strong → strength (vowel changes), wide → width. These are historical changes — learn them as fixed forms.
-th/θ/ · the voiceless 'th' sound as in 'thin'
Tap the button to hear how the ending sounds. Each word in the table has its own audio.
height (not "hight"): from "high" but spelled height. Pronunciation: /haɪt/ = "hite".
length: the -g- comes before the -th. Pronunciation: /leŋkθ/ = "lengkth".
strong → strength (not "strongth"). The vowel changes: strong /ɒ/ → strength /e/.
A trick to remember it
Just 6 words, like a ruler with 6 markings: width, length, height, depth, warmth, strength. Learn them together like the 6 marks on a ruler.
Exercise 1 · Form the word
Exercise 2 · Pick the right one
The noun from "strong" is...
Exercise 3 · Pick the right one
How is "height" pronounced?
The suffix -th turns adjectives into nouns naming a dimension or abstract quality: wide becomes width. In Spanish it usually maps to -ura / -itud / -eza.
The ending -th is pronounced /θ/ · the voiceless 'th' sound as in 'thin'. For example, "width".
"wide" becomes "width". It is a typical example of the -th suffix.
-tion, -ness, -ful, -ly, -able... every ending you need to understand thousands of words at once.