Of string or something stringlike: full of, or tied up, in knots.
Of a part of the body, a tree, etc.: full of knots (knobs or swellings); gnarled, knobbly.
Complicated or tricky; complex, difficult.
Of an austere or hard nature; rugged.
Synonym of rugose: describing an extinct coral of the order †Rugosa.
A coral from that order.