1) Baseless 2) Idle 3) Illogical 4) Unfounded 5) Unprovoked 6) Unsupported 1) Baseless 2) Idle 3) Speculative 4) Tenuous 5) Unfounded 6) Unproven 7) Unsubstantiated 8) Unsupported 9) Unwarranted 10) Without rational basis 11) Without reason 
• (a.) Without ground or foundation; wanting cause or reason for support; not authorized; false; as, groundless fear; a groundless report or assertion.
Ground'less adjective [ Anglo-Saxon grundleás bottomless.] Without ground or foundation; wanting cause or reason for support; not authorized; false; as, groundless fear; a groundless report or assertion. -- Ground'less*ly , adverb --