Strong’s Greek
G4030 — perikephalaia
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
περικεφαλαία
perikephalaia — pronounced per-ee-kef-al-ah'-yah
feminine of a compound of 4012 and 2776; encirclement of the head, i.e. a helmet:--helmet. see GREEK for 4012 see GREEK for 2776
2 occurrences in the KJV.
Ephesians 6:17
And take the helmet of salvation, and the sword of the Spirit, which is the word of God:
1 Thessalonians 5:8
But let us, who are of the day, be sober, putting on the breastplate of faith and love; and for an helmet, the hope of salvation.