Other forms: presumed, presumes, presuming
To presume something is to take it as true without checking, because everything points that way. Nobody answered the door, so I presumed they were out. The letter never arrived, so we presume it was lost.
Presume and assume sit close together, and the difference is evidence: you presume when there is good reason to think so, you assume when you simply take it as given. Law leans on the word — a defendant is presumed innocent, a missing person is presumed dead — and so does polite conversation: you must be Sarah, I presume. There is a second, sharper meaning: to presume is to take a liberty you have no right to, as in I would not presume to tell you how to raise your children. That sense gives presumptuous, for a person who oversteps, and presumption, which is both the belief and the cheek. Presume stands a step above assume in formality.
1verbpresumeTo take something as true without proof, on the strength of what is likely.
“The house was dark, so I presumed everyone had gone to bed.”
2verbtreatTo treat something as true officially until it is shown to be otherwise.
“The court presumes a person innocent until the case is proved.”
3verbdareTo dare to do something you have no right to do.
“I would not presume to give her advice about her own family.”
Also accepted in games: assume, suppose
Latin praesūmere meant to take beforehand, to anticipate: prae-, 'before', plus sūmere, 'to take'. English received it through Anglo-Norman presumer. To presume is to take the conclusion in advance of the proof — and taking things in advance is exactly how the rude second sense grew out of the first.
Proto-Indo-European
*h₁em-
Latin
praesūmere — to take beforehand, anticipate
Anglo-Norman
presumer
Middle English
presumen
English, today
presume
Built from
From Middle English presumen, from Anglo-Norman presumer and its source, Latin praesūmere (“to take beforehand, anticipate”), from prae- + sūmere (“to take”).
Etymology from Wiktionary, CC BY-SA