1. (

• improbable ,
• unlikely ,

) not likely to be true or to occur or to have occurred; "legislation on the question is highly unlikely"; "an improbable event" ;

2. (

• improbable ,
• unbelievable ,
• unconvincing ,
• unlikely

) having a probability too low to inspire belief ;

3. (

• improbable ,
• marvelous ,
• marvellous ,
• tall

) too improbable to admit of belief; "a tall story" ;