Content words are called—

The correct answer is lexical words.

Content words (also known as open class words) carry the main meaning or semantic content of a sentence. They include nouns, main verbs, adjectives, and adverbs. Because these words convey primary information and meaning, they are also called lexical words.

In contrast, function words (or grammatical words / functors) such as prepositions, pronouns, conjunctions, and auxiliary verbs serve to connect content words together grammatically and are sometimes called empty words because they lack independent lexical meaning.