oscillate
     v 1: be undecided about something; waver between conflicting
          positions or courses of action; "He oscillates between
          accepting the new position and retirement" [syn: {hover},
           {vibrate}, {vacillate}]
     2: move or swing from side to side regularly; "the needle on
        the meter was oscillating" [syn: {vibrate}]
Source: WordNet® 2.0