Digraph, often misspelled as diagraph, may refer to:Digraph (orthography), a pair of characters used together to represent a single sound, such as "ch" in English Ligature (writing), the joining of two letters as a single glyph, such as "æ" Digraph (computing), a group of two characters in computer source code to be treated as a single character A directed graph, in graph theory Digraph, a component of a CIA cryptonym, a covert code name Digraph, a two-letter ISO 639-1 language code