n.

1. 冒昧；放肆；自以为是；傲慢[U]
   It is presumption to go to a party when one has not been invited.

   未被邀请而去参加宴会是冒昧的。

2. 推测；假定，设想[C][U][+（that）]
3. 推测的理由（或根据）[C][U]
4. 【律】推定[C][U]

n.

1. an act or instance of presuming something to be the case.
   ▸an idea that is presumed to be true.
   ▸chiefly Law  an attitude adopted towards something in the absence of contrary factors.
2. presumptuous behaviour.