worker

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. One who works at a particular occupation or activity: an office worker.
2. n. One who does manual or industrial labor.
3. n. A member of the working class.
4. n. A member of a colony of social insects such as ants, bees, wasps, or termites, usually a sterile female but often a sexually immature individual of either sex, that performs specialized work such as building the nest, collecting and storing food, and feeding other members of the colony.

Century Dictionary and Cyclopedia

1. n. One who or that which works; a laborer; a toiler; a performer; a doer.
2. n. In entomology, the neuter or undeveloped female of various social hymenopterous and a few other insects, as bees, ants, and termites, which collects pollen, makes honey, builds or fabricates cells or a nest, stores up food, cares for the young, herds and milks the aphids kept as cows, and performs other services for the community of which it is a member. Among bees the worker is distinguished from the queen and the drone, or the perfect female and male. Among ants certain of the workers are specialized and specified as soldiers; these make war and capture slaves. See cuts under Apidæ, Atta, Monomorium, Termes, and umbrella-ant.
3. n. Maker; creator.
4. n. In a carding-machine, one of the urchins, or small card-covered cylinders.
5. n. A leather-workers' two-handled knife, used in scraping hides.

Wiktionary

1. n. A person who performs labor for his living, especially manual labor.
2. n. A nonreproductive social insect, such as ant, bee, termite or wasp.
3. n. computing A thread performing one instance of a particular task within a program.

GNU Webster's 1913

1. n. One who, or that which, works; a laborer; a performer.
2. n. (Zoöl.) One of the neuter, or sterile, individuals of the social ants, bees, and white ants. The workers are generally females having the sexual organs imperfectly developed. See Ant, and White ant, under White.

WordNet 3.0

1. n. a member of the working class (not necessarily employed)
2. n. a person who works at a specific occupation
3. n. sterile member of a colony of social insects that forages for food and cares for the larvae
4. n. a person who acts and gets things done