What is an antonym for digraph?

There isn't a direct antonym for "digraph" in the sense of a word that means the opposite of a digraph.

Here's why:

* Digraph: A digraph is a combination of two letters that represent a single sound. Examples include "sh" (ship), "th" (thin), "ch" (chair).

* Antonyms describe opposite concepts.

Instead of an antonym, you could consider these related concepts:

* Single letter: A single letter that represents a sound, as opposed to two letters.

* Phoneme: The basic unit of sound in a language. A digraph represents a single phoneme.

* Monograph: A single letter representing a single sound (rare, but it could be considered a contrast to the two-letter combination of a digraph).

Ultimately, the best way to express the opposite of a digraph depends on the specific context.