Sentence:  "Leonard": You're clearly upset about Amy being gone, and you're trying to replace her with a bunch of cats. / "Sheldon": Clowder. / "Leonard": What? / "Sheldon": A group of cats is a clowder. Or a <WSD>glaring</WSD>. It's the kind of thing you ought to know now that we have one. 
Meaning of the word marked with <WSD> tags:  A group of cats.