'Peninsula' is Latin for 'almost-island' — 'paene' (almost) + 'insula' (island). Land nearly surrounded.
A piece of land almost entirely surrounded by water but connected to the mainland by a narrow strip; a large body of land projecting into a body of water.
From Latin paeninsula, a compound of paene (almost, nearly) + insula (island). The literal meaning is almost an island — a landmass nearly surrounded by water but remaining connected to the mainland. Paene is of uncertain ultimate PIE origin; it may relate to a root meaning scarcely or barely. Insula (island) may derive from in salō (in the
The German word for peninsula is 'Halbinsel' — literally 'half-island' — which is a calque (loan-translation) that captures the same concept as Latin 'paeninsula' ('almost-island') but uses native Germanic words. Both languages independently decided that a peninsula is a kind of incomplete island, though they disagree on whether it is 'almost' or 'half' of one.