in the Jews' language

Boyd’s Bible Dictionary:

(tongue). Originally one (Gen. 11:1). Diversified at Babel (Gen. 11:7-9).

Concise Bible Dictionary:

The Hebrew language, common to the Jews. Rab-shakeh was asked to speak in the Syrian language (the Aramaic); but he, wishing the people of Jerusalem to understand him, spoke in Hebrew (2 Kings 18:28; Neh. 13:24; Isa. 36:13).

Strong’s Dictionary of Hebrew Words:

Transliteration:
Yhuwdiyth
Phonic:
yeh-hoo-deeth’
Meaning:
feminine of 3064; the Jewish (used adverbially) language
KJV Usage:
in the Jews' language