Adverb
Verb (する)
Onomatopoeic
1.  lightly rolling (of a small and round thing)
2.  pleasant, high-pitched sound (e.g. bell, young woman's laughter)
3.  changing frequently (e.g. conversation, plans);  (occurring) in rapid succession (e.g. sumo wrestlers being defeated);  fickly;  in a fickle manner
4.  roly-poly
5.  chirp chirp (sound of insects)
6.  ribbit ribbit (sound of frogs);  croak croak
7.  roller;  lint roller;  paint roller
when read as "コロコロ, ころころ"