What is Sucker in Poker?

The Sucker (also known as the Mark or the Spot) is the player at a poker table who attracts much attention, largely due to his/her inexperience and lack of skill. The term is commonly used when good players are determining a good table to play at. 

“Listen, here’s the thing. If you can’t spot the sucker in the first half hour at the table, then you ARE the sucker.” – Mike McDermott, Rounders.