Unbetrothed

Elizabeth in consequence remained unbetrothed, and her father soon afterwards secured to himself a more strenuous ally in the earl of Lenox, also of the blood-royal of Scotland, by bestowing upon this nobleman the hand, not of his daughter, but of his niece the lady Margaret Douglas.

Source: wiktionary

The early pledging and marriage of the children has reduced illicit sexual intercourse to a minimum; nevertheless, it sometimes happens that an unbetrothed girl, not a pota, is found to be pregnant.

Source: wiktionary