trigraph
/ˈtraɪɡræf/
noun
- A group of three letters that together represent a single sound, as in 'sch' or 'tch'.
- In English spelling, the trigraph 'eau' is found in words like 'beautiful'.
- The word 'watch' contains the trigraph 'tch' which makes the /tʃ/ sound.
- Teachers explain that 'igh' is a trigraph that spells the long 'i' sound.