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.
- hemichordate
- hemicycle
- hemidemisemiquaver
- hemihedral
- hemihydrate
- hemihydrated
- hemimetabolic
- hemimetabolism
- hemimetabolous
- hemimorphic
- hemimorphite
- hemin
- Hemingway
- hemiparasite
- hemiparasitic
- hemiplegia
- hemiplegic
- hemipteran
- hemipterous
- hemisphere
- hemispheric
- hemispherical
- hemispherically
- hemistich
- hemline