What is the definition of the word truth in the Hebrew?

Answer 1

Specifically, the Hebrew word "truth" (Emet אמת) means the same thing as in English.

More generally, the Hebrew word אמת means according to the ways of God as set forth in the Torah. Thus, for example, Jacob, whom our sages call "the man of truth," was able to bamboozle his conman cousin Laban the Deceitful (see Genesis ch.31), because of the principle set forth in Psalms 18:27. Similarly, when asked how much Talmud you've mastered, you answer with an amount which is lower that your full repertoire, because humility is a Godly attribute (Talmud, Bava Metzia 23b).

Answer 2

Hebrew = אמת (emét)

Greek = Αλήθεια