the.com/coat of mail

means A flexible suit of armor made from thousands of interlinked metal rings, worn to protect the body from blades and arrows.

from From Old French 'cote de maille' — 'cote' meaning a coat or outer garment, and 'maille' meaning mesh or net, itself descending from Latin 'macula,' meaning a mesh or a spot/stitch in a net. So the name is literally just descriptive: a coat made of mesh. The ring-mail technique it describes is far older than the English phrase, with roots likely going back to ancient Celtic or related Iron Age metalworking traditions, later spread widely by Roman and medieval use.