presume (BELIEVE)
verb [T]
to believe something to be true because it is very likely, although you are not certain:
[+ (that)] I presume (that) they’re not coming, since they haven’t replied to the invitation.
[+ speech] You are Dr Smith, I presume?
“Are we walking to the hotel?” “I presume not/so.”
[+ object + adjective] The boat’s captain is missing, presumed dead (= it is believed that he is dead).
In British law, you are presumed innocent until you are proved guilty.
[+ object + to infinitive] The universe is presumed to contain many other planets with some form of life.

presumably
adverb
used to say what you think is the likely situation:
They can presumably afford to buy a bigger apartment.
Presumably he just forgot to send the letter.

presumption
noun [C or U]
when you believe that something is true without having any proof:
The presumption of innocence is central to British law.
There is no scientific evidence to support such presumptions.
[+ that] The decision is based on the presumption that all information must be freely available