n.1. One that sucks, especially an unweaned domestic animal.
2. Informal a. One who is easily deceived; a dupe.
b. One that is indiscriminately attracted to something specified: I'm always a sucker for a good crime drama.
3. Slang a. An unspecified thing. Used as a generalized term of reference, often as an intensive: "our goal of getting that sucker on the air before old age took the both of us" (Linda Ellerbee).
b. A person. Used as a generalized term of reference, often as an intensive: He's a mean sucker.
4. A lollipop.
5. a. A piston or piston valve, as in a suction pump or syringe.
b. A tube or pipe, such as a siphon, through which something is sucked.
6. Any of numerous freshwater fishes of the family Catostomidae of North America and East Asia, having a thick-lipped mouth used for feeding by suction.
7. Zoology An organ or other structure adapted for sucking nourishment or for clinging to objects by suction.
8. Botany A secondary shoot produced from the base or roots of a woody plant that gives rise to a new plant.
v.tr.1. To strip suckers or shoots from (plants).
2. Informal To trick; dupe: sucker a tourist into a confidence game.