Icebound means trapped or surrounded by ice, unable to move or escape. When a ship becomes icebound in Arctic waters, thick ice forms around its hull and holds it in place like a vise, preventing it from sailing forward or backward. The crew must either wait for the ice to melt or use powerful icebreakers to cut a path to freedom.

Explorers in the 1800s and early 1900s faced terrifying situations when their ships became icebound during polar expeditions. Some crews spent entire winters trapped, their vessels frozen solid in place. The famous explorer Ernest Shackleton's ship Endurance became icebound in Antarctic ice in 1915 and was eventually crushed, forcing his crew to survive on ice floes for months.

The word can describe anything locked in by ice: an icebound harbor that ships can't enter or leave, an icebound lake with a surface you can walk across, or an icebound coastline where glaciers meet the sea. Sometimes people use it more broadly to describe feeling stuck or trapped, like being icebound by a blizzard that prevents you from leaving your house.