Yarmulke: a skullcap worn especially by Orthodox and Conservative Jewish males in the synagogue and the home

Source: http://www.merriam-webster.com/dictionary/yarmulke

“eager to discern the exact point when it turned from a black and Hispanic neighborhood to an Orthodox Jewish one, and was delighted when he spotted a guy in a Yarmulke talking to two coffee-colored men.” From a Literary Visitor Strolls in From the Airport by Charles McGrath

The following quote uses the word to explain the religion of the man through what he was wearing. Which creates an image for the reader to visualize while reading this passage.