APOSIOPESIS

(Greek: becoming silent), a speaker's deliberate failure to complete a sentence. Aposiopesis usually indicates speechless rage or exasperation, as in Why, you . . ., and sometimes implies vague threats as in, Why, I'll . . . . The listener is expected to complete the sentence in his mind. In ancient Greek rhetoric, the aposiopesis occasionally takes the form of a pause before a change of subject or a digression.