companion ladder

plural companion ladders

1. nauticalEither of two ladders leading from the raised quarterdeck of a sailing ship to the upper deck.

   Just as I got my head above the companion ladder, I felt an indescribably unpleasant sensation, suddenly, as it were, losing the power of breathing […] .

   1808–10, William Hickey, Memoirs of a Georgian Rake, Folio Society 1995, p. 87

   1 more example

   The flat roof proved a great luxury, for we sat on our housetop at night, which we reached by a species of companion-ladder from below, and enjoyed our elevated position immensely.

   1887, Harriet W. Daly, Digging, Squatting, and Pioneering Life in the Northern Territory of South Australia, page 112