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done randomly; characterized by chance, often in reference to art or music
Aleatoric music incorporates elements of chance in its structure.
from 'aleatory' which derives from 'alea', a die, the dice
"of uncertain outcome," literally "depending on the throw of a die," 1690s, from Latin aleatorius "pertaining to a gamester," from aleator "a dice player," from alea "a game with dice; chance, hazard, risk; a die, the dice;" perhaps literally "a joint-bone, a pivot-bone," and related to axis.