You will almost always meet this word in one fixed phrase: 'the uncrowned king of X' (or 'the uncrowned queen of X'). It means the person everyone treats as the best, the leader, the most famous in some field — even though nobody officially gave them the title. 'He is the uncrowned king of night-market food' means no committee ever voted, but everyone knows. The phrase carries warmth and a bit of playfulness; it is a compliment, and it works because it borrows the picture of a real king. There is a small but real second use, closer to the plain sense of the parts: a real royal person who has not had the crowning ceremony yet, or who never did. History books say things like 'the uncrowned king died before the ceremony'. Learners meet the first use far more often. Two things about its shape: it is used before a noun ('the uncrowned champion'), not after the verb be — you would not say 'she is uncrowned' to mean she is the best. And the field usually follows with 'of': uncrowned king of comedy, of Wall Street, of Taiwanese pop.

無冕王、無冕之王（同 the uncrowned king of…；指公認的第一人、實質上的王者，雖無正式頭銜）