Trigraphs  

A trigraph is a group of three letters that together form a single specific sound. Trigraphs may consist solely of consonants or vowels, or they may be a combination of both.

Before we look at different trigraphs, it’s important to draw a distinction between trigraphs and consonant clusters.

Consonant trigraphs are often confused with consonant clusters (also called consonant blends), which are groups of two to three consonant letters that are pronounced individually in quick succession. For example, the word script contains two consonant clusters: scr and pt. Even though the sounds blend together quickly, the first cluster is not a trigraph and the second cluster is not a digraph, because each letter is pronounced individually: /skrɪpt/.

Another aspect that can cause confusion is that a consonant cluster may also consist of a single consonant combined with a consonant digraph (two letters forming a unique sound), as in school (/skul/) or throw (/θroʊ/). The fact that two of the three letters create a single, specific sound that is then merged quickly with the sound of a third letter (plus the ubiquity of such combinations) makes it seem as though the three together form a single trigraph, but this is not the case.

The most common and perhaps the only true consonant trigraph in English is TCH, which forms the sound /ʧ/.

It almost always appears at the end of base words, as in:

Except when we add suffixes to words like those above, there are only a few instances in which TCH appears mid-word, such as butcher (/ˈbʊʧər/), ketchup (/(ˈkɛʧəp/), and tetchy (/ˈtɛʧi/). There is also a slang word derived from Yiddish that both begins with the trigraph and contains it mid-word: tchotchke (/ˈʧɑʧkə/), meaning “a cheap knick-knack or trinket.”

The consonant digraph CH also commonly forms the /ʧ/ sound, and it can sometime be difficult to determine which spelling to use. However, there are a few simple conventions we can follow.

Other than the slang term tchotchke, words can only begin with the /ʧ/ sound when it is formed from the CH spelling, such as:

You may have noticed that none of the TCH words we looked at earlier featured a “traditional” long vowel sound (i.e., one that “says the name” of the vowel letter); they all had short vowel sounds before TCH.

When long vowel sounds precede the /ʧ/ sound in a word, they are always made by vowel digraphs, in which case /ʧ/ is always spelled CH. Additionally, digraphs that form other vowel sounds will also be followed by CH rather than TCH. For instance:

The only standard exception to this rule is the word aitch (/eɪʧ/), which is the word for the letter H.

When the /ʧ/ sound comes after the consonants L, N, or R at the end of a word, it is always spelled CH. For example:

When the /ʧ/ sound is preceded by a single vowel letter making a short vowel sound, it is much more likely to be spelled TCH, as we saw from the examples earlier. However, there are several exceptions to this rule that will be spelled CH instead. Unfortunately, we just have to memorize these exceptions. Here are the most common:

In most English words, SCH represents a consonant cluster of the sounds /s/ and /k/, as in school, scheme, or schedule, rather than a true trigraph forming a single sound. (However, see the note about schedule further down.)

However, in certain foreign loan words from German and slang words derived from Yiddish, SCH can be used to represent the sound /ʃ/ (like the SH in show). For example:

(*Note that the Yiddish slang terms all have variant spellings beginning “sh-.”)

Finally, it’s worth noting that the word schedule, pronounced /ˈskɛʤul/ in American English, is typically (though not always) pronounced /ˈʃɛdjul/ in British English.

Vowel trigraphs almost always form diphthongs, two vowel sounds that merge or “glide” together into a single compressed sound that acts as the nucleus of a syllable. Less commonly, vowel trigraphs can form triphthongs (three vowel sounds that glide together into one); in some rare instances, they can even reduce to a weak schwa sound /ə/.

This trigraph does not occur natively in English, but it does occur in several French loanwords and words adapted from French.

When it appears at the end of a word, EAU always creates the vowel sound /oʊ/ (the “long” O sound). This is most common in loanwords directly taken from French.

When EAU appears in the middle of a word, though, it can produce three vowel sounds: /ju/ (the “long” U sound), /ɑ/ (the vowel sound in the word cot), or the reduced weak vowel /ə/ (the schwa). Words in which EAU appears mid-word are derived from French, rather than direct loans.

Here are the examples most commonly appearing in English:

When the suffix “-ous” (used to form adjectives from nouns and verbs) attaches to a word, it can end up following the vowels E, I, or U. While -UOUS always creates two syllables with two vowel sounds (/ju.əs/), -EOUS and -IOUS can both result in a single reduced vowel sound (/əs/); we can think of EOU and IOU as vowel trigraphs in such situations.

EOU functions as a trigraph when “-eous” comes after the consonants C and G, or T. (After other consonants, it forms two syllables: /i.əs/.) In addition to making the single vowel sound /ə/, “-eous” also affects the pronunciation of the consonants: C is pronounced /ʃ/, while G is pronounced /ʤ/.

While this isn’t a very common occurrence (especially C + EOUS), let’s look at some examples in which it occurs:

There’s also one unique instance in which EOUS results in a consonant forming the /ʧ/ sound: righteous (/ˈraɪʧəs/). Every other instance of T + EOUS results in the pronunciation /ti.əs/, so we just have to memorize the exceptional way righteous is pronounced.

Like EOU, IOU acts as a trigraph when “-ious” comes after the consonants C and G; unlike EOU, it also functions this way after the consonant T. Once again, “-ious” also affects the pronunciation of the consonants it follows: C and T are both pronounced /ʃ/, while G is pronounced /ʤ/.

While the two endings behave in a similar way, it is much more common for words to end in “-ious” than “-eous.” For example:

If we don’t count words formed with the suffix “-ous,” EAU is the only vowel trigraph that can be found in a variety of words. There are several others, though, that act as standalone words. Each of these ends in E and has either W or Y (which act as vowels in this capacity) as its central letter:

There are two trigraphs that use a combination of vowel and consonant letters: IGH (which forms a vowel sound) and DGE (which forms a consonant sound).

The trigraph IGH always produces the same vowel sound: /aɪ/ (the “long I” sound). It usually occurs in the middle of a word, most commonly followed by the letter T (or when it is used in the first part of a compound word). It can also appear at the end of a word without a consonant following it, but this is much less common.

Notice that we don’t include any examples in which IGH appears after the vowels A (as in straight) or E (as in neighbor). In these cases, the four letters are working together to form a single sound, sequences known as tetragraphs; we’ll look at these more closely in a separate section.

The letter combination DGE is typically considered a trigraph because the three letters always function together to form the same sound as the letter J (/ʤ/). For example:

It’s worth mentioning that we can also consider DG separately as a consonant digraph. (We include DG in the consonant digraphs section of this guide.) For instance, in words in which DGE is followed by N or T (as in smidgen and budget), the letter E makes its own vowel sound, which goes against the concept of a trigraph making a single indivisible speech sound.

Additionally, words that end in DGE will have E omitted when a vowel suffix is added such as “-ing” (bridging, judging, etc.) or “-y” (dodgy, edgy, etc.), but DG will still retain the /ʤ/ pronunciation. Silent E is still required to form this sound initially, but the digraph DG can stand on its own in a suffixed word and still create this sound.

Regardless, distinguishing between the digraph DG and the trigraph DGE is not especially important, so long as it is clear that the word is forming the /ʤ/ sound when DG is present.

Finally, it’s worth nothing that in British English (Received Pronunciation), the letter R is not normally pronounced as a consonant when it follows a vowel sound within the same syllable; instead, it can elongate the existing vowel sound, reduce it to a schwa (/ə/), or else alter it into a diphthong or triphthong. R can therefore combine with vowels to form trigraphs that we would normally not include in American English.

We won’t spend too much time on them here, but let’s look at a few examples of the combinations and sounds these trigraphs might make. (The IPA transcriptions for these examples will include the long vowel mark [ ː ] to reflect how they normally are written in Received Pronunciation.)