1. gnarl -- (twist into a state of deformity; "The wind has gnarled this old tree")
2. murmur, mutter, grumble, croak, gnarl -- (make complaining remarks or noises under one's breath; "she grumbles when she feels overworked")
gnarl can be used as a noun
1. knot, gnarl -- (something twisted and tight and swollen; "their muscles stood out in knots"; "the old man's fists were two great gnarls"; "his stomach was in knots")
1.
Unless thy prudence fail thee, dost not mark How they do gnarl upon us, and their scowl Threatens us present tortures. - from The Divine Comedy, Complete by Dante Alighieri