BachelorA bachelor is an unmarried man; some restrict the usage to men who have never been married.
See also Bachelor of Arts.
The following was originally from the 1911 Encyclopedia Britannica. As such, it may not yet be properly adapted to Wikipedia (obsolete, typos, no accidental links, etc.). It is included as a stub of sorts to inspire people to modify it:
BACHELOR (from Med. Lat. baccalarius, with its late and rare variant baccalaris~cf. Ital. baccalare-through 0. Fr. bacheler), in the most general sense of the word, a young man. The word, however, as it possesses several widely distinct applications, has passed through many meanings, and its ultimate origin is still involved in a certain amount of obscurity. The derivation from Welsh bach, little, is mentioned as " possible " by Skeat (Etymological Dictionary), but is "definitely discarded" by the Oxford English Dictionary, and that given here is suggested as probable. The word baccalarius was applied to the tenant of a baccalaria (from baccalia, a herd of cows, bacca being a Low Latin variant of vacca), which was presumably at first a grazing farm and was practically the same as a vaselleria, i.e. the fief of a sub-vassal. Just, however, as the character and the size of the baccalaria varied in different ages, so the word baccalarius changed its significance; thus in the 8th century it was applied to the rustici, whether men or women (baccalariae), who worked for the tenant of a mansus. Throughout all its meanings the word has retained the idea of subordination suggested in this origin. Thus it came to be applied to various categories of persons as follows.- (i) Ecclesiastics of an inferior grade, e.g. young monks or even recently appointed canons (Severtius, de episcopis Lugdunen-sibus, p. 377, in du Cange). (2) Those belonging to the lowest stage of knighthood. Knights bachelors were either poor vassals who could not afford to take the field under their own banner, or knights too young to support the responsibility and dignity of knights bannerets (see KNIGHTHOOD AND CHIVALRY). (3) Those holding the preliminary degree of a university, enabling them to proceed to that of master (magister) which alone entitled them to teach. In this sense the word baccalarius or baccalaureus' first appears at the university of Paris in the 13th century, in the system of degrees established under the auspices of Pope Gregory IX., as applied to scholars still in statu pupillari. Thus there were two classes of baccalarii: the baccalarii cursores, i.e. theological candidates passed for admission to the divinity course, and the baccalarii dispositi, who, having completed this course, were entitled to proceed to the higher degrees. In modern universities the significance of the degree of bachelor, in relation to the others, varies; e.g. at Oxford and Cambridge the bachelor can proceed to his mastership by simply retaining his name on the books and paying certain fees-; at other universities a further examination is still necessary. But in no case is the bachelor a full member of the university. The degree of bachelor (of arts, &c.) is borne by women also. (4) The younger or inferior members of a trade gild or city company, otherwise known as "yeomen" (now obsolete). (5) Unmarried men, since these presumably have their fortunes yet to make and are not full citizens. The word bachelor, now confined to men in this connotation, was formerly sometimes used of women also.
Bachelors, in the sense of unmarried men, have in many countries been subjected to penal laws. At Sparta, citizens who remained unmarried after a certain age suffered various penalties. They were not allowed to witness the gymnastic exercises of the maidens; and during winter they were compelled to march naked round the market-place, singing a song composed against themselves and expressing the justice of their punishment. The usual respect of the young to the old was not paid to bachelors (Plut. Lye. 15). At Athens there was no definite legislation on this matter; but certain minor laws are evidently dictated by a spirit akin to the Spartan doctrine (see Schomann, Gr. Alterth. i. 548). At Rome, though there appear traces of some earlier legislation in the matter, the first clearly known law is that called the Lex Julia, passed about 18 B.C. It does not appear to have ever come into full operation; and in A.D. 9 it was incorporated with the Lex Papia et Poppaea, the two laws being frequently cited as one, Lex Julia et Papia Poppaea. This law, while restricting marriages between the several classes of the people, laid heavy penalties on unmarried persons, gave certain privileges to those citizens who had several children, and finally imposed lighter penalties on married persons who were childless. Isolated instances of such penalties occur during the middle ages, e.g. by a charter of liberties granted by Matilda I., countess of Nevers, to Auxerre in 1223, an annual tax of five solidi is imposed on any man qui non habet uxorem et est bache-larius. In Britain there has been no direct legislation bearing on bachelors; but, occasionally, taxes have been made to bear more heavily on them than on others. Instances of this are the act (6 and 7 Will. III.) passed in 1695; the tax on servants, 1785; and the income tax, 1798.