St Giles' Greek

(cant) A secret language, as spoken by beggars and thieves.

Japanese Meaning

乞食や盗賊が使う隠語、秘密の言語

He could speak St Giles' Greek so fluently that no outsider could understand their bargains.

彼は乞食や盗人が使う隠語を非常に流暢に話したので、部外者には彼らの取引が理解できなかった。

Sense（1）

(cant) A secret language, as spoken by beggars and thieves.