an unknown and unpredictable phenomenon that causes an event to result one way rather than another; "bad luck caused his downfall"; "we ran into each other by pure chance"
an unknown and unpredictable phenomenon that leads to a favorable outcome; "it was my good luck to be there"; "they say luck is a lady"; "it was as if fortune guided his hand"
having no cause or apparent cause; "a causeless miracle"; "fortuitous encounters--strange accidents of fortune"; "we cannot regard artistic invention as...uncaused and unrelated to the times"
having no justifying cause or reason; "a senseless, causeless murder"; "a causeless war that never had an aim"; "an apparently arbitrary and reasonless change"