Etymology and distribution of 定作.

The Japanese surnames etymology dictionary.
https://play.google.com/store/apps/details?id=info.jigensha.jcedfreeGoogle Play で手に入れよう https://apps.apple.com/us/app/id1471109324
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Popuration of 定作.

カンマ区切りで複数の名字を指定できます。

Etymology of 定作

Distribution of 定作
Ranking
1 Katsuura-gun Katsuura-chou(About 30)
2 Ito-gun Katsuragi-chou(Very rare)
2 Nanto-shi(Very rare)
2 Hiroshima-shi Nishi-ku(Very rare)
2 Komatsushima-shi(Very rare)
2 Tokushima-shi(Very rare)
2 Naruto-shi(Very rare)