noun - A lido is a public outdoor swimming pool in the United Kingdom and some other countries. On a cruise ship, outdoor pools and the surrounding facilities are referred to as the lido deck.
The term lido is an Italian word for beach and forms part of the place name of several Italian seaside towns known for their beach (e.g. Lido di Venezia, the barrier beach enclosing the Lagoon of Venice). The term possibly found its way into English from returning English visitors to Lido di Venezia, where sea-bathing took place from the late 19th century. The word was first used for a public outdoor swimming pool in the UK in July 1935, in London.