(n.) Three letters united in pronunciation so as to have but one sound, or to form but one syllable, as -ieu in adieu; a triphthong.
TRIGRAPH
Meaning of TRIGRAPH in English
Webster's English dictionary. Английский словарь Webster. 2012
(n.) Three letters united in pronunciation so as to have but one sound, or to form but one syllable, as -ieu in adieu; a triphthong.
Webster's English dictionary. Английский словарь Webster. 2012