What does "bachelor" mean?

Additional senses

1. 2.A person who has taken the first or lowest degree in the liberal arts, or in some branch of science, at a college or university; as, a bachelor of arts.
2. 3.A knight who had no standard of his own, but fought under the standard of another in the field; often, a young knight.
3. 4.In the companies of London tradesmen, one not yet admitted to wear the livery; a junior member. [Obs.]
4. 5.(Zoöl.) A kind of bass, an edible fresh-water fish (Pomoxys annularis) of the southern United States.