What does defilade mean?
Defilade is a military term denoting protection from enemy observation and direct fire achieved by interposing terrain or an obstacle between a position and the threat. A unit 'in defilade' sits behind a ridge, embankment, wall, or trench so that hostile gunners cannot see or strike it along a direct line of sight. The word functions as both noun and verb: soldiers may seek defilade on the reverse slope of a hill, or a commander may defilade his vehicles in a sunken road before advancing. It belongs firmly to professional military register—armor tactics, artillery siting, and infantry doctrine—and has no everyday figurative meaning. Its natural counterpart is 'enfilade,' which describes the opposite situation: a position exposed lengthwise to sweeping fire. The term entered English from French during the eighteenth century, when linear tactics and siegecraft made the geometry of fire and cover a matter of life and death. Understanding defilade illuminates why soldiers prize reverse slopes, hedgerows, and dead ground, and why modern tank crews speak of 'hull-defilade' and 'turret-defilade' positions.
Protection from hostile observation or direct fire provided by a natural or artificial obstacle interposed between a position and the threat; the state of being so sheltered.
"The mortar team moved into defilade behind the levee as soon as the counter-battery fire began."
Frequently modified in armored-warfare contexts: 'hull defilade' conceals the hull while leaving the turret exposed, and 'full defilade' or 'complete defilade' conceals the entire vehicle.
To place (troops, weapons, vehicles, or a position) under such protection from enemy fire or observation.
"They defiladed the anti-tank guns on the far side of the ridge before dawn."
Rarely pluralized in practice; the uncountable form is standard, though plural occurs when referring to multiple distinct covered positions.
"The battalion occupied several defilades along the wadi's northern bank."
The word that keeps tanks alive comes from French for 'threading' through a line — soldiers literally hide by staying off the enemy's line of sight.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of defilade
Defilade derives from the French verb défiler, formed from dé- ('to undo, remove') plus fil ('thread'), originally meaning to march past in single file like a threaded strand. In eighteenth-century military usage, the derived sense came to mean shielding troops from fire along an enemy's line, since a defiladed force was removed from the 'thread' or line of sight of hostile guns. English adopted the term directly from this French military vocabulary, alongside its cousin 'enfilade.' The same root fil gives us 'file' (a line of people), 'filament,' and 'profile' (literally a drawn outline, from drawing a thread).
Related word forms
How defilade is actually used
Defilade is technical military vocabulary, used almost exclusively in armed-forces contexts such as armor tactics, artillery siting, and field engineering. It carries no figurative use in general speech. The related term 'enfilade' is its tactical opposite: enfilade exposes troops along the axis of fire, while defilade protects against it. The verb form is transitive and often appears in passive constructions ('the position was defiladed').
Easily confused with defilade
A defile is a narrow mountain pass or ravine (or, as a verb, to march in single file), whereas defilade is the protective shielding of troops or vehicles behind terrain or obstacles.
Despite visual similarity, decollate means to separate sheets of paper or to behead, sharing no connection with defilade's military sense.