Trigraph may refer to:

• Trigraph (orthography), a combination of written letters used to represent a sound

• 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

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

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

• Digraph (disambiguation)
• Tetragraph
• Multigraph (disambiguation)