1. In Modern English, the gender of those nouns that apply to either sex, as spouse, parent, or mouse.

2. In some languages, the gender of those nouns that may be either masculine or feminine but not neuter, as Latin parēns, "parent," or bōs, "ox, cow."

3. In some languages, the gender of those nouns belonging to the single gender derived from the earlier masculine and feminine genders and separate from the neuter gender, as in Hittite or modern Danish.