Dictionary.net

• Generally, the period of puberty is considered to be the age at which both sexes are nubile. They are truly nubile, however, only when they are fitted to procreate healthy and vigorous children, and are competent to discharge their duties as parents.

1846 - Medical lexicon: a dictionary of medical science
By Robley Dunglison

• Marriageable; capable of fertilizing or of being fertilized. [Lat.]

1916 - Appleton's medical dictionary
By Smith Ely Jelliffe