What this suffix does
The suffix -ure takes a verb and creates a noun naming the result, process or state of that action. From "fail" you get "failure"; from "mix" you get "mixture"; from "press" you get "pressure".
It is one of the most frequent suffixes in English, but irregular: it does not always sound or form the same way. The best strategy is to learn the most common -ure words directly as vocabulary.
Three groups of -ure words
1. Result of an action: failure, mixture, closure, exposure.
2. Abstract state or condition: pressure, pleasure, leisure, measure.
3. Fixed -ure words with no obvious root: nature, culture, future, figure, picture.
The third group is fixed vocabulary to be learned by heart.
Pronunciation: two main patterns
-ure is pronounced two ways depending on the preceding consonant:
After t, s, x: sounds like /tʃər/ = "cher": nature = NAY-cher, picture = PIK-cher, mixture = MIK-cher.
After other consonants: sounds like /ər/ = "er": failure = FAIL-yer, pleasure = PLEH-zher, measure = MEH-zher.
The final /r/ is soft in American English and nearly silent in British English.
A trick to remember it
The most frequent -ure words are: failure, mixture, pressure, pleasure, nature, culture, future, picture, feature, measure. Learn them as fixed vocabulary.