The Collaborative International Dictionary
Diphthongal
Diphthongal \Diph*thon"gal\ (?; 115), a. Relating or belonging to a diphthong; having the nature of a diphthong. -- Diph*thon"gal*ly, adv.
Wiktionary
diphthongal
a. Pertaining to a diphthong.
Usage examples of "diphthongal".
The landlady wore a look of aggrieved hauteur, and when she spoke her accent was more refined and wholly diphthongal than usual.