Gnarled, knotty, twisted.
A knot in wood; a large or hard knot, or a protuberance with twisted grain, on a tree.
Something resembling a knot in wood, such as in stone or limbs.
To knot or twist something.
To snarl or growl; to gnar.
That groans.
Heavily laden, as if to creak under the strain.
A low sound associated with extended suffering, sorrow, and toil.