The belted plaid is a large blanket-like piece of fabric which is wrapped around the body with the material pleated or, more accurately, loosely gathered and secured at the waist by means of a belt. Wikipedia

Large blanket-like piece of fabric which is wrapped around the body with the material pleated or loosely gathered and secured at the waist by means of a belt; part of Highland dress Wikidata

A large blanket-like piece of fabric, worn wrapped around the body with the material loosely gathered and secured at the waist by means of a belt; a standard item of men's Highland dress from the late 16th century until the middle of the 18th century, and the precursor of the modern kilt. Wiktionary