Here's the breakdown:
* Phonetically: A triphthong is a single vowel sound made up of three distinct vowel qualities gliding smoothly from one to the other.
* English: English doesn't have a lot of clear-cut, distinct triphthongs. Some linguists argue that English only has two:
* /aɪə/ (as in "fire") - A glide from /aɪ/ (like "eye") to /ə/ (the schwa sound).
* /aʊə/ (as in "hour") - A glide from /aʊ/ (like "ow" in "cow") to /ə/.
* Other possibilities: Some linguists consider sounds like /eɪə/ (as in "player") and /ɔɪə/ (as in "boy") to be triphthongs, but they are more complex and debated.
The bottom line: While English is often said to have two triphthongs, there's no universally agreed-upon number.