tumbler doll; self-righting doll
A traditional roly-poly toy that rights itself when pushed over. This term is literary and uncommon in everyday speech; the more familiar word is 起き上がり小法師 (おきあがりこぼし) or simply だるま.
See also: 起き上がり小法師 (おきあがりこぼし)
A 不倒翁 is a lucky toy that rights itself immediately when knocked over.
不倒翁 is a literary or archaic word for the same tumbler doll, whereas 起き上がり小法師 is the everyday modern term.
From Chinese 不倒翁 (bùdǎowēng), literally 'old man who does not fall'. The Japanese reading is on'yomi.