How we change what others think, feel, believe and do
Aposiopesis is stopping a sentence before it has been grammatically completed.
I wandered lonely as a...
If I gave you what you wanted, would you...
This is the best since...
If you touch her I'll, I'll...
We all have a deep need for the comfort of certainty, which translates into completion of activities and even sentences. Completing a sentence (or anything) gives the desired comfort of closure. Hence when a person does not complete a sentence, we feel a strong compulsion first to think about what the ending might be and, if they do not speak further, to fill the silent void, most probably with our guessed completion.
Using aposiopesis, one usually starts a sentence and then stops, leaving a 'pregnant pause'. This invites the other person to complete the sentence, either in their imagination or even speaking out loud.
The completion of the sentence may also be rhetorical, where both speaker and audience know the answer and it needs not be said, for example when a person is being suggestive.
Aposiopesis may also imply that the speaker is so overcome by emotion (from passion to anger) they are unable to speak further. It can also signal modesty or uncertainty.
Aposiopesis is Greek for 'becoming silent'.