Word Origin & History
gnarl
"contort, twist," 1814, a back-formation from gnarled, which appears only in Shakespeare ("Measure for Measure," 1603) but was picked up 19c. by romantic poets and brought into currency. It is probably a variant of M.E. knar "knot in wood" (1382), originally "a rock, a stone," of uncertain origin. Gnarly first attested 1829; picked up 1970s as surfer slang to describe a dangerous wave; it had spread in teen slang by 1980s, where it meant both "excellent" and "disgusting."