These are the iron spikes driven through Jesus's hands (and feet) to fasten him to the cross. The word appears only in John 20:25, both times in Thomas's skeptical declaration: 'Unless I see in his hands the mark of the nails, and place my finger into the mark of the nails, and place my hand into his side, I will never believe.' The double mention emphasizes Thomas's empirical demands—he wants tangible proof, specifically the nail wounds. Classical Greek used the term for ornamental studs, shoenails, and ordinary fasteners, but here it carries the full horror of crucifixion's brutality.