A piece of leg armor, or a soldier wearing such armor; a variant or related term to cuisse or cuish used in medieval military contexts.
Possibly from Old French cuisse plus -ard (a suffix often indicating a person characterized by something), or a regional variant spelling of cuisse with a different ending.
Cuissard might be a word that historians debate—it could be a real military term or a variant spelling that got copied into old texts and confused later scholars!
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