What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
The sixth letter of the early Greek alphabet preserved in the Aeolic dialect.
Mid 17th century; earliest use found in Edward Stillingfleet (1635–1699), bishop of Worcester and theologian. After classical Latin Aeolicum digammon; compare Aeolica littera Aeolic letter, and also French digamma éolique.