Definition of peninsulate in US English:

peninsulate

verb

  • with object Of water: to surround (a piece of land) almost completely; to make into a peninsula, divide into peninsulas.

Origin

Mid 16th century; earliest use found in John Leland (c1503–1552), poet and antiquary. From peninsula + -ate, after insulate.

Pronunciation

peninsulate

/pɪˈnɪnsjʊleɪt/