The term Chaser is used by drinkers. It means a drink of something bland or sweet to follow-up a straight shot of something like whiskey, gin, rum or tequila. It is called a chaser because it is drunk quickly after the initial strong shot of liquor which has a high alcohol content. John Collier used the word in his title The Chaser because the story talks about the love potion. A man named Alan Austen wants to acquire a love potion from an obscure apothecary. It symbolizes what Alan is doing to Diana that is, he is chasing her love. A chaser is something you drink after drinking something else possibly something unpleasant. The life cleaner offers the inevitable chaser to the love potion Alan buys to make Diana love him.