A clattering, rattling, or loud confused noise; a noisy disturbance or commotion.
From Middle English bratel, possibly imitative in origin (imitating the sound of rattling), related to Old English brat (something that makes noise). The word evolved to mean any loud, confused sound.
The word 'brattle' is onomatopoetic—it actually sounds like what it means, which is why old English writers used it for scenes of chaos and why we still find it in descriptions of battle or disorder.
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