The -tion and closely related -sion and -ation suffixes are among the most frequently used stress-controlling suffixes in American English. All of these suffixes cause the syllable previous to the -tion or -sion to carry the main stress of the word. This hugely important pattern provides a formula to determine which syllable is likely to be the stressed syllable in an enormous number of words in English.
In addition to studying the following example words to learn these stress patterns, note other commonalities in their pronunciation to help learn the characteristics of pronouncing the suffixes themselves correctly.
-tion suffix: sh sound and ch sound
The -tion is pronounced with an sh sound unless the sound preceding the suffix is an s sound; then the suffix is likely to be pronounced with a ch sound. Of the two options, the sh sound pronunciation is much more common.
-sion suffix: sh sound and zh sound
The -sion suffix is likely to be pronounced with a zh sound when it is preceded by an r sound or a vowel sound (this often aligns with the ssion spelling). In most other circumstances, the sh sound is the more likely pronunciation for the -sion suffix. Since both of these pronunciation patterns are common in American English, care should be taken with the pronunciation of all words containing the -sion suffix.
Variations of the -tion, -sion and -ation suffixes
The -tion, -sion and -ation suffixes can be viewed as base suffixes for still more related suffixes, namely -tional, -tionally, -sional, -sionally, -ational and -ationally. The syllable stress pattern remains consistent, even when more syllables are added to the word: the syllable previous to the -tion or -sion carries the word's primary stress.
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