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"
(of a clause) unable to stand alone syntactically as a complete sentence; "a subordinate (or dependent) clause functions as a noun or adjective or adverb within a sentence"