Synonyms for Gas chamber:

n.

crucifixion, death sentence, death row, capital punishment, the chair, the death penalty, behead, death warrant, execute. gas chamber (noun)
death chamber.
punishment device (noun)
electric chair, stocks, rawhide, cowhide, noose, solitary confinement, bull whip, guillotine, lash, thong, truncheon, torture chamber, rope, thumbscrew, rack, whip, block, strap, gallows, cane, stake, captivity, switch, iron, jail, maiden, gibbet, birch rod, rod, prison, pillory, whipping post, ax, scaffold.

Other synonyms:

Other relevant words:
crucifixion, death chamber, capital punishment.