What is the term for a word that appears alone at the end of a paragraph?

The term for a word that appears alone at the end of a paragraph is known as a "widow." In typography, a "widow" refers specifically to a short line or a single word that is left hanging at the bottom of a paragraph or column, separated from the rest of the text. This can disrupt the visual flow of a page and is often considered undesirable in professional typesetting and layout design.

On the other hand, the term "orphan" refers to a similar concept but is used to describe the first line of a paragraph that appears alone at the bottom of a page or column. While both terms deal with the placement of text, "widow" specifically pertains to the end of a paragraph, making it the correct choice in this context. The other options—"single" and "fragment"—do not specifically refer to this typography issue and are generally not used to describe positioning of words in paragraph formatting.