Difference between Assume and Presume

Key Difference: Presume means to believe something without significant proof. It can also mean to take up responsibilities or duties. Assume means to take something for granted without proper proof. It could also mean to take up duties or take up a commanding role. A main difference between assume and presume is ‘as’ and ‘pre’, ‘As’ means ‘towards’, ‘pre’ means ‘prior to.’

Assume and presume are most commonly found in language or literature, but these words can be used in any subject. These words nearly synonymous and many dictionaries use one word to define the other. In general sense, both the words mean to accept without detailed investigation.

In order understand what the words actually mean, let’s look at the dictionary definition of these words.

According to Merriam-Webster dictionary, presume is defined as “to undertake without leave or clear justification; to expect or assume especially with confidence and to suppose to be true without proof.”

From the definition we can see that presume means to believe something without significant proof. It can also mean to take up responsibilities or duties. It also is used in legal terms, ex: The defendant was presumed innocent, until proven otherwise.

While assume is defined as, “to take up or in; to take into partnership, employment, or use; to take to or upon oneself; to place oneself in; to take as granted or true.”

The definition gives a few different uses of assume. Assume means to take something for granted without proper proof. It could also mean to take up duties or take up a commanding role, ex: The king assumed the throne at a very young age. Assuming can be used in the term where a person believes something based on similar situations that may have happened before, ex: I assume he will be late, as always.

A very popular saying used in today’s generation is “Assume means making an ‘ass’ of ‘u’ and ‘me’.” This is mostly used as a caution to tell people that assuming means to believe something without significant proof and can lead to some bad decisions, so it is best not assume.

A main difference between assume and presume is ‘as’ and ‘pre’. This difference is a significant one as ‘as’ means ‘towards’, while ‘pre’ means ‘prior to.’

	Assume	Presume
Definition	To take up or in; to take into partnership, employment, or use; to take to or upon oneself; to place oneself in; to take as granted or true.	To undertake without leave or clear justification; to expect or assume especially with confidence and to suppose to be true without proof.
Origin	Middle English, from Latin ‘assumere’	Middle English, from Late Latin & Anglo-French; Anglo-French ‘presumer’
Time	15th century	14th century
Synonyms	accept, bear, shoulder, take over, undertake	assume, conjecture, daresay, imagine, guess, speculate, suppose, surmise, suspect, suspicion
Antonyms	disavow, disclaim, disown, repudiate	Do not take for granted, disbelieve