木偶の坊

Etymology
Phrase consisting of. The deku portion is of unknown origin and may have arisen as a standalone term later than as a part of a compound. Theories include:
 * Alteration from, used synonymously, in turn from , literally "little one who has gone mad".
 * From, through dekurubō.
 * From Sino-Japanese.

The third theory is problematic semantically and does not account for the intermediary dekurubō pronunciation.

Noun

 * 1) doll, puppet
 * 2) useless person