[di.graph] n (1780) 1: a group of two successive letters whose phonetic value is a single sound (as ea in bread or ng in sing) or whose value is not the sum of a value borne by each in other occurrences (as ch in chin where the value is /t/ + /sh/)
2: a group of two successive letters
3: ligature
4. -- di.graph.ic adj -- di.graph.i.cal.ly adv