In sports gambling, the term “sharp” is used to refer to intelligent and astute bettors.
A card shark is expert player who is capable of taking advantage of less skilled opponents. However, please note that in American English, the term “card sharp” has some negative connotations and might be used to indicate cheating or other forms of foul play.
1. “Because Lisa spent many hours studying every football game and always bet on the right team, she was considered one of the sharps by her friends.”
2. “Never trust a card sharp, those people will always find a way of taking your chips and making you look stupid.”
As a synonym of the term “shark,” the term “sharp” used to refer to people who prey upon others and is derived from German “Schorke” or “Schurke” (rogue, rascal). The term had extremely negative connotations – calling someone a sharp was an equivalent to accusing him of cheating. The positive connotations of “expert” and “professional player” did arise later on. However please note that in American English “shark” is informally considered to be the more positive term, while “sharp” retained its negative meaning to a larger extent.