Content words (nouns, verbs, adjectives, adverbs) carry the primary meaning in a text and serve as a cohesive device by creating lexical chains that tie sentences together. When content words are repeated or related words are used across a text, they create coherence. This is different from imagery (a literary device), ellipsis (omitting words), or proposition (a complete thought unit). Content words are fundamental to textual cohesion through lexical relationships.