gnarl       
noun [ C ] uk/nɑːl/ us/nɑːrl/
 木节,木瘤
a rough or twisted lump on a tree or piece of wood
  The boy stared at the notches and gnarls in the trunk of the oak. 男孩瞪眼看着橡树干上的凹痕和木节。 
 - More examples
 - He brings out the character of each wooden piece by making features of the gnarls and knots.
 - The great age of the trees was almost tangible, the gnarls and knots of these stunted, moss-encrusted forms suggesting any number of gothic fantasies.
 - Although the "wood" has realistic knots, gnarls and woodworm holes, it's made of hardened polyurethane.
 - Because it's been moulded from a piece of oak, it's got all the knots and gnarls of real wood.