Lexical Definition

‎γέεννα‎ géenna (gheh'-en-nah) hell: Gehenna ^N:N--T
of Hebrew origin (‎גַּיְא‎ and ‎הִנֹּם‎)

hell.

• valley of (the son of) Hinnom
• ge-henna (or Ge-Hinnom), a valley of Jerusalem, used (figuratively) as a name for the place (or state) of everlasting punishment

Abbott-Smith

† γέεννα (γέενα, Mk 9:45, Rec.), -ης, ἡ (perh. through Aram. גֵּיהִנָּם, from Heb. גֵּי הִנֹּם, Ne 11:30; גֵּי בֶּן הִנֹּם, Jo 18:16; גֵּי בּנֵי הִנֹּם, IV Ki 23:10; valley of (the son, sons of) lamentation); [in LXX the nearest approach to γ. is γαίεννα, Jos 18:16 (Γαὶ Ὀννόμ, A), elsewhere φάραγξ Ὀνόμ (Jos 15:8, al.), V. Swete on Mk 9:43 ;]
Gehenna, a valley W. and S. of Jerusalem, which as the site of fire-worship from the time of Ahaz, was desecrated by Josiah and became a dumping-place for the offal of the city. Later, the name was used as a symbol of the place of future punishment, as in NT: Mt 5:29, 30 10:28, Mk 9:43, 45, 47, Lk 12:5, Ja 3:6; γ. τ. πυρός, Mt 5:22 18:19, prob. with ref. to fires of Moloch (DB, ii, 119b); υἱὸς γεέννης, Mt 23:15; κρίσις γεέννης, 23:33.†

Abbott-Smith References

Liddell-Scott-Jones

γέεννα, ης, ἡ,

Hebrew gé-hinnóm, the valley of Hinnom, which represented the place of future punishment, [NT]

_{LSJ Scripture Refs: Matt.5.22}