yo-yo vs plaything

yo-yo and plaything both are nouns.

Word	Noun	Adjective	Verb	Adverb
yo-yo	Yes	No	No	No
plaything	Yes	No	No	No

As nouns, plaything is a hypernym of yo-yo; that is, plaything is a word with a broader meaning than yo-yo:

yo-yo: a toy consisting of a spool that is reeled up and down on a string by motions of the hand
plaything: an artifact designed to be played with

Other hypernyms of yo-yo include toy.

yo-yo (noun)	plaything (noun)
a toy consisting of a spool that is reeled up and down on a string by motions of the hand	an artifact designed to be played with