an extremely large mass of ice floating in the sea 冰山（浮在海上的巨大冰块） The ship struck a hidden iceberg. 船撞上了一座隐藏的冰山。
Oxford Collocations DictionaryIceberg is used before these nouns:- lettuce
Word Originlate 18th cent.: from Dutch ijsberg, from ijs ‘ice’ + berg ‘hill’.
Idioms
the tip of the iceberg
only a small part of a much larger problem （问题的）冰山一角 This figure represents only the tip of the iceberg, since as many as 90% of cases go unreported. 这个数字只是冰山一角，因为多达90%的病例没有报告。