Sluicing

Definition
Sluicing is reducing a wh-question to its wh-phrase(s) in a context where the omitted part can be reconstructed from the preceding sentence.

Example
In (i) the content of the complement clause of know is understood as which sonata's Susan has played.

(i) Susan has played some sonata's, but I don't know which sonata's __

Sentences like (i) raise the question whether there is an empty category following which sonata's, and if so, how it is licensed (see licensing).

Origin
The term goes back to Ross (1969).

Links
Utrecht Lexicon of Linguistics