Merriam-Webster Collegiate Dictionary - floater

 noun  Date: 1717  1.  a. one that floats  b. a person who floats something  2. a person who votes illegally in various polling places  3.  a. a person without a permanent residence or regular employment  b. a worker who moves from job to job; especially one without fixed duties  4. a pitched, thrown, or hit ball that moves through the air relatively slowly with little or no spin or rotation  5. a policy insuring specific items of personal property (as jewelry or art)  6. a bit of optical debris (as a dead cell or cell fragment) in the vitreous body or lens that may be perceived as a spot before the eye; also a spot in the visual field due to such debris — usually used in plural