独楽 is read as こま (koma) and means spinning top.
こま
koma
どくそうがっき
solo instrument
はなごま
cardboard spinning top, shaped and coloured like a flower
きょくごま
top
ばいごま
spinning top (traditionally made of Japanese babylon shell)
どくとく
understood only by oneself
ひとりごと
soliloquy
ひとりあるき
taking on a life of its own (of a rumour, etc.)
どくじ
independent
どくりつ
independence (e.g. of a nation)
どくさい
running (a company, etc.) despotically
どくしん
single
どくせん
hogging