Толковый словарь английского языка - yo-yo

I. noun (plural ~s) Etymology: probably from Ilocano yóyo, or a cognate word in a language of the Philippines Date: 1915 a thick grooved double disk with a string attached to its center axle that is made to fall and rise to the hand by unwinding and rewinding on the string, a condition or situation marked by regular fluctuations from one extreme to another, a stupid or foolish person, II. adjective Date: 1932 shifting back and forth or up and down uncertainly or unexpectedly, III. intransitive verb (~ed; ~ing) Date: 1967 to move from one position to another repeatedly ; fluctuate