(trademark in the UK)
■ noun ( plural ~s )
1》 a toy consisting of a pair of joined discs with a deep groove between them in which string is attached and wound, which can be spun alternately downward and upward by its weight and momentum as the string unwinds and rewinds.
↘a thing that repeatedly fluctuates.
2》 informal, chiefly N. Amer. a stupid, insane, or unpredictable person.
■ verb ( ~es , ~ing , ~ed ) move up and down repeatedly; fluctuate.
Origin
1915: prob. ult. from a lang. of the Philippines.