lobster [OE] Lobsters and locusts [ME] are linguistically the same. Latin locusta, from which both derive, had both meanings. A look at close-up pictures of the two clearly shows the similarity. Lobster was used as a contemptuous name for British soldiers from the mid 17th century. Originally applied to a regiment of Roundhead cuirassiers who wore complete suits of armour; later the term was associated with the red military coats once worn by British soldiers. In US slang, lobster was used to describe ‘a slow-witted or gullible person’ from the late 19th century.