What term is used to describe the grammatical number category referring to two or more items or units?

The term that refers to the grammatical number category indicating two or more items or units is "plural." In English grammar, singular indicates one item or unit, whereas plural denotes multiple items or units. For instance, the plural form of "cat" is "cats," which refers to more than one cat. This distinction is fundamental in understanding how nouns and pronouns function within sentences, allowing for clarity in communication. Recognizing plural forms helps in ensuring grammatical accuracy when discussing quantities in both writing and speech. Therefore, the correct answer effectively captures the essence of this grammatical category.