Presumable, a.
Etymology: [Cf. F. présumable.]
Such as may be presumed or supposed to be true; that seems entitled to belief without direct evidence.
Shades of meaning
Fernald has no entry of its own for presumable; he lists it under apparent, likely.
Where he writes about it:
Presumable implies that a thing may be reasonably supposed beforehand without any full knowledge of the facts. — from apparent
A thing is conceivable of which the mind can entertain the possibility; a thing is conjectural which is conjectured as possible or probable without other support than a conjecture, or tentative judgment; a thing is presumable which, from what is antecedently known, may betaken for granted in advance of proof. — from likely