Final answer:
A widow is a place where justification switches from left to centered, creating a visual disruption on the page.
Step-by-step explanation:
When Keegan pointed out a widow, he was referring to a place where justification switched from left to centered. A widow is a single line or word that appears at the top of a page while the rest of the paragraph or text is at the bottom of the previous page. This disrupts the visual flow and can make the page look unbalanced.