The Welsh Not was a token used by teachers at some schools in Wales in the 19th century and early 20th century to discourage children from speaking Welsh at school, by marking out those who were heard speaking the language. Accounts suggest that its form and the nature of its use could vary from place to place, but the most common form was a piece of wood suspended on a string that was put around the child's neck. Terms used historically include Welsh not, Welsh note, Welsh lump, Welsh stick, cwstom, Welsh Mark, and Welsh Ticket.

Welsh is a Celtic language of the Brittonic subgroup that is native to the Welsh people. Welsh is spoken natively in Wales, by some in England, and in Y Wladfa.