What is an affix?

An affix is indeed defined as an additional element that is added either to the beginning (prefix) or the end (suffix) of a root word to modify its meaning or create a new word. This linguistic component plays a crucial role in word formation and can significantly change the meaning of the root word. For instance, by adding the prefix "un-" to the word "happy," you create "unhappy," which conveys the opposite meaning. Affixes are fundamental in understanding how words can be expanded and altered in the English language, making the correct characterization essential for grasping vocabulary and meaning.

The other choices focus on unrelated concepts. A complex sentence structure refers to a grammatical construct rather than word formation. Literary devices encompass a range of techniques used in writing but do not relate specifically to affixes. Lastly, a word that carries multiple meanings describes a polysemous word, not the concept of an affix at all.