Definitions:

1. A large consolidated mass of floating sea ice, that typically occurs in polar regions, such as the Arctic and Antarctic, and is driven by wind, currents, and tides. NOUN
   • Ships navigating the polar seas must be cautious of the shifting pack ice, which can trap vessels.
2. Refers to a large expanse of floating sea ice that forms when individual pieces of ice, known as floes, cluster together and become a continuous, moving sheet. NOUN
   • In winter, the Arctic Ocean becomes covered with thick pack ice, making navigation difficult.

Synonyms:

• floe
• ice pack
• sea-ice