noun
fast ice
Technical term in oceanography and glaciology for sea ice that is attached to the coastline, sea floor, or grounded icebergs and does not move with currents or winds.
南極の沿岸では、冬になると広範囲に定着氷が発達する。
Along the Antarctic coast, fast ice develops extensively in winter.
流氷 is drift ice that moves with ocean currents and wind, while 定着氷 is stationary fast ice attached to land or grounded features.
Compound of 定着 (ていちゃく, 'fixed, attached') and 氷 (ひょう, 'ice'). The term is a direct calque of the English 'fast ice' (where 'fast' means 'secure, fixed').