hairdressing of a sumo wrestler's top-knot
Refers specifically to the styling of a sumo wrestler's traditional top-knot (mage). Used in sumo contexts.
The hairdressing of the top-knot is one of the important preparations for a sumo wrestler.
Compound of 髷 (mage, 'top-knot') and 結い (yui, 'tying, binding'), from the verb 結う (yuu).