Or they take indefinite adjectives, and they don't actually use a noun to describe exactly what we're speaking about.
或者他们使用不定形容词，实际上他们并没有使用名词来准确描述我们所说的内容。
英语百科
Indefinite pronoun
An indefinite pronoun is a pronoun that refers to non-specific beings, objects, or places.
Indefinite pronouns can represent either count nouns or noncount nouns and include a number of sub-categories: universal (such as everyone, everything), assertive existential (such as somebody, something), elective existential (such as anyone, anything), and negative (such as nobody, nothing).