a gnarly tree or branch is rough and twisted with hard lumps [= gnarled]
gnarly hands or fingers are twisted, rough, and difficult to move, usually because they are old [= gnarled]
3 American English spoken
a word meaning very good or excellent, used by young people:
'Look at the size of that wave.' 'Gnarly!'
4 American English spoken
a word meaning very bad, used by young people:
a gnarly car wreck