yo-yo

yo-yo ► NOUN (pl. yo-yos) 1) (trademark in the UK) 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. 2) a thing that repeatedly falls and rises again.

► VERB (yo-yoes, yo-yoed) ▪ move up and down repeatedly; fluctuate.

ORIGIN probably ultimately from a language of the Philippines.