A conjunction is a part of speech that connects words, phrases, or clauses in a sentence. It serves to link ideas and can show relationships such as addition, contrast, or cause. For example, in the sentence "I want to go for a walk, but it's raining," the word "but" is a conjunction that connects the two contrasting ideas.
The word "conjunction" comes from the Latin word "coniunctio," which means "a joining together." The prefix "co-" means "together," and "iunctio" comes from "iungere," meaning "to join."