Sluicing is a linguistic phenomenon where a part of a sentence is omitted, typically a wh-clause, while still allowing the meaning to be understood. For example, in the sentence "I know who is coming, but I don't know who," the second "who is coming" is omitted, yet the listener can infer the missing information. This construction often occurs in questions and can help streamline communication. Sluicing is commonly seen in everyday conversation and is a topic of interest in the study of syntax and semantics, as it reveals how language can convey meaning efficiently while leaving out certain details.