Trigraph

Trigraph may refer to:

Computing

 * Digraphs and trigraphs (programming), a group of characters used to symbolise one character
 * An octal or decimal representation of byte values
 * Mnemonics for machine language instructions
 * As language codes in ISO 639

Cryptography

 * As substitution group in a substitution cipher
 * As combinations in the Ling Qi Jing

Mathematics

 * As a generalization of graphs where there is a set of edges called semi-adjacent

Other uses

 * Trigraph (orthography), a sound representation in orthography