Definition: In language, a diphthong is a gliding vowel sound normally represented by two adjacent vowels.
In typography, some diphthongs are represented by a single ligature character (joined letters). The most commonly used diphthong ligatures in English that are also found in many fonts are:
- æ (ae) and Æ (AE) (Alt+0230 and Alt+0198)
- œ (oe) and Œ (OE) (Alt+0156 and Alt+0140)
Some words, such as encyclopædia, are commonly spelled by replacing the diphthong with its most prominent vowel sound (encyclopedia). Others, such as subpœna, are written with two separate letters rather than the actual œ character (subpoena). Although they are a type of ligature, these characters are not accessed via the OpenType ligatures feature in page layout software. And unlike ligatures which can be edited as if they are two separate characters and don't generally trigger the
misspelling feature of software, these diphthongs are treated as a single letter and may be identified by software as a spelling error.
Also Known As: gliding vowel
Common Misspellings: dipthong | diphtong | dipthon | difthon
