1) Probable 2) Supposable 3) Surmisable 4) Thinkable 1) Supposable 2) Surmisable 3) Thinkable 
• (a.) Such as may be presumed or supposed to be true; that seems entitled to belief without direct evidence.
Pre·sum'a·ble adjective [ Confer French présumable .] Such as may be presumed or supposed to be true; that seems entitled to belief without direct evidence. 
[adj] - able to be inferred on slight grounds
supposable adjective capable of being inferred on slight grounds
capable of being taken for granted; probable.