Longman Dictionary of Contemporary English - falter

~ v 1 to become weaker and unable to continue in an effective way  (The economy is showing signs of faltering. | My mother's iron grip upon the household never faltered.) 2 to speak in a voice that sounds weak and uncertain, and keeps stopping  (Laurie's voice faltered as she tried to thank him.) 3 to become less certain and determined that you want to do something  (We must not falter in our resolve.) 4 to move unsteadily because you suddenly feel weak or afraid  (She faltered for a moment.)