(1):

(n.) One who floats or swims.

(2):

(n.) A float for indicating the height of a liquid surface.

(3):

A person who votes illegally in various polling places or election districts, either under false registration made by himself or under the name of some properly registered person who has not already voted.

(4):

A person, as a delegate to a convention or a member of a legislature, who represents an irregular constituency, as one formed by a union of the voters of two counties neither of which has a number sufficient to be allowed a (or an extra) representative of its own.

(5):

A voter who shifts from party to party, esp. one whose vote is purchasable.