From Longman Dictionary of Contemporary Englishbe kingbe kingPOPULARif something is king at a particular time, it has a big influence on peopleback in the days when jazz was king →kingExamples from the Corpusbe king• The new king, I suppose, if you can be king without a land.• In the arts, too, contentionis king.• In Ephyre, the city later called Corinth, Glaucus was King.• During the middle 1800s, cottonproductionwas king in the South.• As at the weight-loss programs I attended in junior high, the scalewas king here.• In 1995, it was stock -- not cash -- that was king.• He was born to be King and was looking for a princess.• If the flounder still exists it will be king. - foreign words and phrasesscattered here and there!