a play among children in which they are seated upon the opposite ends of a plank which is balanced in the middle, and move alternately up and down.-a plank or board adjusted for this play.-a vibratory or reciprocating motion.-same as crossruff.-to move with a reciprocating motion; to move backward and forward, or upward and downward.-to cause to move backward and forward in seesaw fashion.-moving up and down, or to and fro; having a reciprocating motion.