insular [M16th] The earliest use of insular, in the mid 16th century, was as a noun meaning ‘an islander’. Islanders were popularly regarded as narrow-minded and ignorant of people and cultures outside their own experience, and the adjective insular later developed this meaning. The word itself goes back to Latin insula ‘island’, the source also of isle (see island), and of insulate [M16th], and insulin [E20th]. The hormone insulin, produced by the pancreas, gets its name from the islets of Langerhans, the group of pancreatic cells that secrete it. Paul Langerhans was the 19th-century German anatomist who first described them.