yo-yo

A toy consisting of a spheroidal or cylindrical spindle having a circular groove in which string is wound; it is used by holding the string in the fingers and reeling the spindle up and down by movements of the wrist.

A volatile market that moves up and down.

(informal) Someone who vacillates.

(informal) A foolish, annoying or incompetent person.

A cloth rosette formed by gathering the outside edge of a circle of fabric in toward the centre using a running stitch.

A dogfighting maneuver involving the attacker temporarily exchanging altitude for airspeed, or vice versa, in order to rapidly catch up with the defender or to prevent an overshoot.

To vacillate; to move up and down.