bacheler

Old French bacheler meant a young man in the first stage of knighthood — a squire or junior knight, someone who served under a senior knight's banner and had not yet established himself enough to maintain his own knights. The word's ultimate origin is uncertain: possibly from a Latin root meaning cow-herder, or from a Germanic source for a small farm. The knightly meaning was the one that dominated in medieval usage.

As formal knighthood became less the central path to adult male status, bachelor drifted. It retained the sense of someone young and not yet fully established — and the most obvious way an adult man was not yet fully established in medieval society was that he was unmarried and without a household. By the 14th century, bachelor meant an unmarried man alongside the knightly meaning.

University usage was established in medieval Latin: baccalaureus was the first degree granted after completing the basic arts curriculum. The baccalaureus was a novice scholar, the equivalent of the novice knight — still in training, not yet a master. Bachelor of Arts, Bachelor of Science, Bachelor of Laws: the degree system adopted the knightly progression metaphor.

Bachelor has had far better luck than spinster in avoiding stigma — a bachelor is often presented as enviably free, the 'confirmed bachelor' as someone who has made a lifestyle choice. The asymmetry between bachelor and spinster — same marital status, completely different social connotations — is one of the clearest examples of sexist encoding in the English lexicon.