Sentence:  What was the <WSD>something</WSD> the pilot saw, the <WSD>something</WSD> worth killing for? 
Meaning of the word marked with <WSD> tags:  An object whose name is forgotten by, unknown or unimportant to the user, e.g., from words of a song. Also used to refer to an object earlier indefinitely referred to as 'something' (pronoun sense).