The noun θυρεός literally means "door-like" (from θύρα, door), designating the large oblong shield that covered most of the body, shaped somewhat like a door. This distinguished it from the smaller round shield (ἀσπίς). The Roman scutum, the heavy infantry's primary defensive equipment, fits this description. Ephesians 6:16 instructs believers to take up "the shield of faith," using θυρεός to emphasize comprehensive protection—a shield that covers the whole person. The image draws on Roman military practice familiar to the epistle's audience. Translations uniformly render it "shield" (Spanish "escudo," German "Schild"), with the large, body-covering type understood.