What is Bachelor?

Legal Definition
A bachelor is a man who is socially regarded as able to marry, but has not yet.

It is also the title of anyone of any gender or marital status who holds a bachelor's degree.
-- Wikipedia
Legal Definition
The first degree taken at the universities in the arts and sciences, as bachelor of arts, & c. It is called, in Latin, Baccalaureus, from bacalus, or bacillus, a staff, because a staff was given, by way of distinction, into the hands of those who had completed their studies. Some, however, have derived the word from baccalaura, others from bas chevalier, as designating young squires who aspire to the knighthood. (Dupin.) But the derivation. of the word is uncertain.
-- Bouviers Law Dictionary
Legal Definition
The holder of the first or lowest degree conferred by a college or university, e. g., a bachelor of arts, bachelor of law, etc. A kind of inferior knight; an esquire, A man who has never been married.
-- Black's Law Dictionary
Legal Definition
An inferior knight; a squire.
-- Ballentine's Law Dictionary