Assume and presume both mean to believe something before it happens, but when you assume you're not really sure. If someone bangs on your door in the middle of the night, you might assume (and hope!) it's your crazy neighbor. If your neighbor knocks on your door every night at 6:30, at 6:29 you can presume she's coming over in a minute.
To assume is to suppose or believe something without any proof. It also means to take over, usually responsibilities and duties, such as with a job, or to take on a look or attitude:
First, based on your question, we'll assume you're a recent college graduate. (USA Today)
Receiving no reply, three days later he sent a second missive, in which he assumed that his first letter had gone astray. (Elizabeth S. Kite)
"I won't have him," said Sir Henry at once, his eyes assuming their most prawnlike expression. (Mary Cholmondeley)
Presume is from the Latin pre "before" and sumere "to take," like taking something for granted. It means to be sure of something before it happened. When you presume, you suppose something without proof, based on probability:
In her latest video, Britney Spears arrives on earth — an alien, we presume — to spread the message of consumerism. (Washington Post)
I favor the latter explanation, also known as a sensibly presumed truth, just as I believe William Shakespeare wrote a few plays in his day. (Time)
People don't love it when you assume, based on the catchy phrase that calls you an ass, because you're basically making a guess. When you assumed it was your neighbor knocking on your door and you told her to go away, you found out later it was your mom! There's no funny phase about presume, because you're usually right.
Assume isn't only used to mean accept as truth without checking, it also means take on the form of. It might be safer if you don't assume that the vampire standing in front of you isn't merely a person assuming that form.Continue reading...
If you presume something, it means you act as though it's true before all the evidence is in. If you are presumed to be the fastest runner, don't get too cocky — that word implies that you haven't actually raced yet.Continue reading...