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Study Dictionary
Bolt
BOLT [ISBE]
BOLT - bolt (na`al, "to bind up"): The ancient Hebrews had fastenings of wood or iron for the doors of houses (2 Sam 13:17,18; Song 5:5), city gates (Neh 3:3,6,13-15), prison doors, etc. (Isa 45:2), which were in the form of bolts. These were sometimes pushed back from within; but there were others which, by means of a key, could be unfastened and pushed back from without (Jdg 3:23 ff). These were almost the only form of locks known.See BAR; LOCKS.
In Hab 3:5, resheph (a poetic word for "flame") is rendered "fiery bolts" (the King James Version "burning coals"). It seems to denote "the fiery bolts, by which Yahweh was imagined to produce pestilence or fever" (Driver, Deuteronomy, 367).
M. O. Evans
Also see definition of "Bolt" in Word Study