the.com/drydock

means A dock that can be drained of water, used to build or repair ships below their waterline while they rest on dry supports.

from A straightforward compound of 'dry' and 'dock'—the basin that normally floats a vessel is sealed off and pumped empty so workers can reach the hull. The practice dates back centuries, with early versions dug and drained by hand or sluice gates well before steam pumps made the job quick; the word simply names the plain, useful fact that the water is gone.