Gender is a grammatical feature, in a family with person, number, and case. In the languages that have grammatical gender—according to a representative typological sample, almost half of the languages in the world—it is a property that separates nouns into classes. These classes are often meaningful and often linked to biological sex, which is why many languages are said to have a “masculine” and a “feminine” gender. A typical example is Italian, which has masculine words for male persons (il bambino “the.
Across the languages of the world, gender systems vary widely. They differ in the number of classes, in the underlying assignment rules, and in how and where gender is marked. Since agreement is a definitional property, gender is generally absent in isolating languages as well as in young languages with little bound morphology, including sign languages. Therefore, gender is considered a mature phenomenon in language.
Gender interacts in various ways with other grammatical features. For example, it may be limited to the singular number or the third person, and it may be crosscut by case distinctions. These and other interrelations can complicate the task of figuring out a gender system in first or second language acquisition. Yet, children master gender early, making use of a broad variety of cues. By contrast, gender is famously difficult for second-language learners. This is especially true for adults and for learners whose first language does not have a gender system. Nevertheless, tests show that even for this group, native-like competence is possible to attain.