A card sharp (also card shark, sometimes hyphenated or spelled as a single word) is a person who uses skill and/or deception to win at card games (such as poker). "Sharp" and "shark" spellings have varied over time and by region.
The label is not always intended as pejorative, and is sometimes used to refer to practitioners of card tricks for entertainment purposes. In general usage, principally in American English and more commonly with the "shark" spelling, the term has also taken on the meaning of an expert card gambler who takes advantage of less-skilled players, also called an "advantage player", without any implication of actual cheating at cards, in much the same way that "pool shark" or "pool hustler" can (especially when used by non-players) be intended to refer to a skilled player rather than a cheater or swindler. The synonym to "card sharp", "blackleg", when used with reference to card-playing and swindlers, has pejorative connotations.[1]
A card sharp or shark (by either of the gambling-related definitions) may be a "rounder" who travels, seeking out high-stakes games in which to gamble.