diph·thong 
(dĭfthông′, -thŏng′, dĭp-)
(dĭfthông′, -thŏng′, dĭp-)n.
A complex speech sound or glide that begins with one vowel and gradually changes to another vowel within the same syllable, as (oi) in boil or (ī) in fine.
[Middle English diptonge, from Old French diptongue, from Late Latin diphthongus, from Greek diphthongos : di-, two; see DI-1 + phthongos, sound.]
diph·thongal adj.
- Indo-European root: sū-
- Indo-European root: tag-
- Indo-European root: tauro-
- Indo-European root: tegu-
- Indo-European root: tek-
- Indo-European root: teks-
- Indo-European root: telə-
- Indo-European root: tem-
- Indo-European root: ten-
- Indo-European root: terkw-
- Indo-European root: ters-
- Indo-European root: terə-
- Indo-European root: terə-
- Indo-European root: teutā-
- Indo-European root: teuə-
- Indo-European root: tkei-
- Indo-European root: to-
- Indo-European root: tolkw-
- Indo-European root: tong-
- Indo-European root: treb-
- Indo-European root: trei-
- Indo-European root: trep-
- Indo-European root: treud-
- Indo-European root: tu-
- Indo-European root: ud-