A bigraph is another term for a bipartite graph - in mathematics, a graph whose vertices can be divided into two disjoint sets.
A consonant bigraph is a combination of two consonant letters that make a single sound, such as "sh" in ship or "ch" in chat. They are often taught in phonics to help students understand sound blends in words.
"Bipartite" refers to a graph or network that can be divided into two sets of vertices such that all edges connect vertices from one set to the other, with no edges within the same set. A bipartite graph is also known as a bigraph.