Noun inflection refers to the grammatical changes that nouns undergo to express different meanings, such as number, case, or gender. For example, in English, the noun cat can become cats to indicate more than one. This process helps clarify the role of the noun in a sentence. Different languages have various systems of noun inflection. In Spanish, for instance, nouns change their endings to reflect gender, with niño (boy) and niña (girl). Understanding noun inflection is essential for proper sentence structure and meaning in any language.